^^        \l0  OF  THK 


d^If 


JVo. 

Division 
Range 
Shelf 


Digitized  by  tine  Internet  Archive 

in  2008  witii  funding  from 

IVIicrosoft  Corporation 


littp://www.arcliive.org/details/agriculturalqualOOcaldricli 


AGRICULTURAL 

QUALITATIVE   AOT)   QUANTITATIVE 

CHEMICAL    ANALYSIS. 


E.    WOLFF,   FRESENIUS,    KROCKER,   AND  OTHERS. 


EDITED    BY 

G.   C.   CALDWELL, 

I>B0FES80B  OF  AGRIOXTLTtJRAL  CHEMISTKY  IN  THE  OORKELL  VmrSBSltr. 


NEW   YORK: 
ORANGE   JUDD   AND   COMPANY, 

245     BROADWAY. 


Entered  according  to  Act  of  Congress,  in  the  year  1869,  by 
ORANGE    JUDD    &    CO., 

In  the  Clerk's  Office  of  the  District  Court  of  the  United  States  for  the  Southern 
District  of  New  York. 


PREFACE. 


The  purpose  of  this  work  is  to  supply  a  complete 
manual  of  chemical  analysis,  for  the  use,  especially,  of 
agricultural  students. 

The  qualitative  and  quantitative  processes  that  are  de- 
scribed refer  only  to  such  substances  as  are  found  in  soils, 
plants,  animals,  fertilizers,  or  other  materials  or  products 
of  agriculture  ;  and,  moreover,  in  order  to  reduce  the  size, 
and  consequently  the  cost  of  the  book  as  much  as  possi- 
ble, except  in  two  or  three  instances,  only  those  methods 
of  analysis  are  introduced  which  are  most  commonly 
used  by  good  chemists,  and  have  been  tried  and  found 
reliable,  with  such  improvements  as  have  been  made  in 
more  recent  practice. 

The  chapters  on  Special  Analyses  consist,  in  the  main, 
of  a  translation  of  the  "  Anleitung  zur  Chemischen  ITn- 
tersuchung  landwirthschaftlich-wichtiger  Stoffe^  von  Dr. 
Mnil  Wolff,  2te  Aifflage,  1867,"  a  work  of  the  first  au- 
thority in  Germany ;  two  or  three  unimportant  matters 
have  been  omitted,  the  arrangement  has  been  somewhat 
altered,  and  some  additions  have  been  made  to  the  original. 

The  other  chapters,  on  reagents,  manipulation,  etc.,  ^re 
3 


IV  PREFACE. 

made  up  largely  from  the  "  Anleitung  zur  Quantitativen 
Chemischen    Analyse,   von    Dr.    C.    JR.    Fresenius,    5te 

Auflage,  1866." 

Concerning  late  improvements  in  methods  of  analysis, 
the  Zeitschrift  far  Analytische  Chemie,  by  the  same  au- 
thority, has  been  frequently  consulted. 

The  scheme  of  qualitative  analysis  has  worked  well  in 
my  own  hands,  and  with  my  own  students,  but,  neverthe- 
less, I  would  have  preferred  to  give  it  a  more  careful 
trial  before  publishing  it. 

Valuable  assistance  in  testing  this  and  other  methods 
of  analysis  has  been  received  from  Mr.  T.  B.  Comstock, 
while  a  student  in  my  laboratory. 

The  use  of  the  old  system  of  atomic  weights,  and  of 
the  old  nomenclature,  would  doubtless  have  made  the 
book  more  simple  to  the  majority  of  students  at  first,  but, 
nevertheless,  it  seemed  more  expedient  to  follow  the  com- 
mon usage  in  the  best  recent  works  on  chemistry.  The 
same  may  be  said  in  regard  to  the  use  of  the  centigrade 
thermometer  and  the  metric  s}stem  of  Aveights  and 
measures. 

Although  the  work  has  been  somewhat  hastily  prepared 
to  meet  a  pressing  want  in  my  own  laboratory,  I  trust  it 
may  yet  be  found  to  answer  a  good  purpose  in  other  lab- 
oratories where  agricultural  chemistry  is  made  a  specialty. 

G.  C.  C. 

Cornell  University^  College  of  ) 
Agriculture,  August,  1869.    f 


TABLE    OF    CONTENTS. 


CHAPTER  L— Tlte  Reagents. 

List  of  the  reagents  neeclcd,  with  directions  for  preparing  them,  when 
not  more  readily  obtained  otherwise,  and  for  testing  their  purity.    7 

CHAPTER    II.— Analytical   IVIanipnlation. 

Determination  of  specific  gravity,  solution,  evaporation,  precipita- 
tion, filtration  (including  Buiisen's  new  method),  weijihiug  of 
residues  and  precipitates,  measuring  and  dividing  solutions,  and 
calculation  of  results 23 

CHAPTER    III.— Keactions  and  IVIeHiods  ol*  Qnantita- 
tlve  Estimation. 

Potassium,  sodium,  ammonium,  barium,  calcium,  magnesium,  alumin- 
ium, iron,  manganese,  zinc,  lead,  copper,  and  arsenic;  silicic, 
sulphuric,  carjjonie,  phosphoric,  nitric,  hydrochloric,  hydrocyanic, 
hydroferrocyanic,  hydrosulphuric,  hydriodic,  hydrofluoric,  oxalic, 
acetic,  tartaric,  citric,  malic,  lactic,  \iric,  hippuric,  and  tannic 
acids;  cellulose,  starch,  gum,  the  sugars,  albuminoids,  urea,  fat, 
and  alcohol J^ 

CHAPTER    IV.— Special  Mctltods  ol*  Analysis. 

Course  of  qualitative  analysis,  estimation  of  water,  of  organic  mat- 
ter, of  sulphur  and  chlorine  in  organic  compounds,  special 
methods  of  separation  of  bases  and  acids,  schemes  of  analysis. ..128 

CHAPTER    v.— Analysis  of  Soils  and  Rocks. 

Mechanical  and  chemical  analysis,  and  examination  of  physical  prop- 
erties, of  soils,  and  examination  of  marl,  limestone,  and  clay 16.5 


VI  TABLE    OF    CONTENTS. 

CHAPTER   VI.— Fertilizers. 

Farm-yard  manure,  urine,  solid  excrements,  bone-meal,  bone  black, 
bone-ash,  phosphorite,  guano,  superphosphate,  gypsum,  salt, 
potash  compounds,  and  Chili  saltpetre 213 

CHAPTER   VII.— Aslies. 
Ashes  of  plants,  of  animal  substances,  and  of  fuel 241 

CHAPTER   VIIL— Fodder  and  Food. 

Fodder  plants,  beets,  turnips,  potatoes,  seeds,  meal,  flour,  milk, 
butter,  cheese,  and  vinegar 251 

CHAPTER   IX.— IVool  and  Bark. 

Examination  of  wool  and  tanners'  bark 269 


CHAPTER   X.— Beverages. 

Water  and  wine .271 

CHAPTER    XI.— Xal»les. 

Metric  system  of  weights  and  measures,  atomic  weights  of  elements, 
factors  for  calculating  analyses,  estimation  of  tannin  in  bark,  etc.284 


AGRICULTURAL 

QUALITATIVE  AND  QUANTITATIVE 

CHEMICAL     ANALYSIS. 


CHAPTER    I. 

REAGENTS. 

The  following  list  contains  all  the  reagents  used  in  the 
various  courses  of  analysis  described  in  this  book,  arranged 
in  alphabetical  order.  .  Most  of  them  can  be  procured  of 
the  druggists,  or  the  dealers  in  apparatus  and  chemicals. 

Directions  are  given  here  for  the  preparation  of  such 
reagents  only  as  cannot  be  thus  obtained  conveniently. 
The  chemical  tests  to  which  each  reagent  should  be  sub- 
jected, in  order  that  the  analyst  may  be  assured  of  its 
purity,  and  the  strength  of  the  solutions  to  be  made,  are 
also  given,  wlien  it  is  necessary.  Most  of  this  information 
is  taken  from  the  works  of  Fresenius. 

The  new  system  of  nomenclature  and  the  new  formulas 
being  adopted  in  this  work,  the  new  name  and  formula 
of  each  reagent  are  given  first,  and,  for  the  benefit  of 
those  who  are  less  familiar  with  these,  the  old  name  and 
formula  are  afterwards  enclosed  in  parentheses,  whenever 
there  is  any  essential  difference  between  the  new  and  the 
old. 

7 


8  §    1.       KEAGENTS. 

1.  «.— Acid,  acetic— HC,H30,.   (HO,C,H303.  HO, a.) 

— This  should  leave  no  residue  on  evaporation,  and 
should  emit  no  empyreumatic  odor  when  evaporated  after 
saturation  with  sodic  carbonate ;  neither  hydrosulphuric 
acid,  argentic  nitrate,  nor  baric  chloride  should  produce 
any  change  in  it,  nor  amnionic  sulj^hide,  after  neutraliza- 
tion with  ammonia. 

h.  Acid,  Citric— H3CJI,0,.  (3H0,C,,H,0,,.)— Recrys- 
tallize  it,  unless  clean  and  colorless. 

c.  Acid,  hydrochloric — HCl.  (Chlorhydricacid.  Mu 
riatic  acid.) — This  must  be  colorless,  and  it  should  leave 
no  residue  when  evaporated  on  platinum  foil,  nor  should 
it  attack  the  foil ;  it  should  give  no  blue  color  to  starch- 
paper,  nor  should  it  bleach  starch  that  has  been  faintly 
colored  blue  with  iodine ;  it  should  give  no  turbidity  with 
baric  chloride,  after  having  been  considerably  diluted,  nor 
should  it  be  colored  by  hydrosulphuric  acid  or  potassic 
sulphocyanate. 

For  the  dilute  acid,  add  the  concentrated  acid  to  4  parts 
of  water. 

d.  Acid,  hydrosulphuric— H^S.  (HS.)— Pour  dilute 
sulphuric  acid  through  a  funnel  tube  over  fused  ferrous 
sulphide,  in  a  common  bottle,  and  conduct  the  gas  that  is 
evolved,  first  through  water  in  a  small  wash-bottle,  and 
then  into  distilled  water.  The  solution  should  emit  a 
strong  odor  of  sulphuretted  hydrogen,  and  should  be 
freshly  made. 

e.  Acid,  nitric— HNO3.  (HO,NO,.)— This  should  be 
colorless,  and  should  leave  no  residue  when  evaporated  on 
platinum  foil ;  after  having  been  considerably  diluted,  it 
should  not  be  made  turbid  by  argentic  nitrate  or  baric 
chloride.  For  the  dilute  acid,  add  the  concentrated  acid 
to  4  parts  of  water. 

/.  Acid,  nitro-hydrochloric  Aqua  regia.— Mix  to- 
gether 1  part  of  pure  nitric  acid,  and  3  or  4  parts  of  pure 
hydrochloric  acid. 


§    1.       EEx\.GEXTS.  9 

g.  Acid,  oxalic,— H^C^O,.  (2H0,C,0,.)  This  should 
not  present  the  least  appearance  of  efflorescence ;  it 
should  give  a  perfectly  clear  solution  with  water,  and 
sliould  leave  no  residue  when  ignited  in  a  platinum  dish. 
If  the  acid  does  not  meet  these  requirements,  it  should  be 
purified  by  repeated  recrystallization. 

Stolba  {Fresenius^  Zeitschrift  8,  63)  recommends  subli- 
mation as  a  convenient  method  of  purifying  oxalic  acid. 

Dry  the  acid  thoroughly  by  keeping  it  in  a  warm  place 
for  a  considerable  time,  with  occasional  stirring  ;  when  a 
small  portion  of  it,  gently  heated  in  a  test  tube,  gives  off 
but  little  water  before  subliming,  it  is  sufficiently  dry. 
Put  it,  then,  in  a  large  beaker  to  the  depth  of  15-20  mm., 
cover  the  beaker  with  a  hollow  cone  of  paper,  and  im- 
bed it  in  iron  turnings  in  an  iron  dish,  to  the  same  depth 
as  that  of  the  acid  inside,  and  heat  it  cautiously,  raising 
the  temperature  very  gradually.  Scrape  off  the  outside 
of  the  cone  of  sublimed  acid,  separate  the  more  solid  yel- 
lowish outer  part  from  the  white  inner  portion,  and  purify 
each  by  itself  by  crystallization  from  solution  as  usual. 

h.  Acid,  sulphuric— H,SO,.  (H0,S03).  —  Common 
sulphuric  acid  usually  contains  lead,  wdiich  is  precipitated 
as  a  fine  w^hite  powder,  when  the  acid  is  diluted  with  con- 
siderable water,  or  when  mixed  with  4  or  5  parts  of 
alcohol;  it  sometimes  gives  a  red  color  with  a  solution  of 
ferrous  sulphate,  where  the  two  liquids  come  in  contact  (§ 
62),  and,  when  diluted,  gives  the  reaction  for  chlorine  with 
aigentic  nitrate  (§  63),  and  for  arsenic  by  Marsh's  test 
(§  57).  The  pure  acid  should  give  none  of  these  reac- 
tions, nor  any  blue  color  after  dilution  with  20  parts  of 
water,  when  a  little  starch  paste  and  potassic  iodide  are 
added  to  the  cooled  liquid ;  it  should  be  volatilized  com- 
pletely when  heated. 

The  dilute  acid  is  pre}xired  by  adding  the  concentrated 
acid  to  5  parts  of  water,  slowly,  and  with  constant   stir- 
ring, letting  the  mixture  stand  a  long  time  if  any  plumbic 
1*  ' 


10  §   2-       KEAGENTS. 

sulphate  is  precipitated,  and  then  decanting  the  clear  su- 
pernatant liquid  for  use. 

i.  Acid,  silicic. — See  Quartz. 
h.  Acid)  taniliC)  needs  no  testing. 

2,  Alcohol.— C^H^O.  (C.H^O,.)— This  is  used  both  in 
its  pure  state  (absolute  alcohol),  and  mixed  with  water 
until  its  specific  gravity  is  0.83  or  0.84,  corresponding 
to  about  90° I  „  of  pure  alcohol,  by  volume. 

It  should  be  volatilized  completely,  and  leave  no  odor 
of  fusel  oil  when  rubbed  between  the  hands  ;  it  should 
burn  with  a  pale  blue,  barely  visible  flame,  and  should 
not  redden  blue  litmus-j)aper. 

3.  a. — Ammonic  acetate. — NH.C^HgO^.  (Acetate  of 
ammonia.  NHp,C,H303.  NIip,A.)— This  should  be 
colorless,  free  from  empyreumatic  oclor,  and  inorganic 
acids,  and  should  be  completely  volatilized  when  heated. 

h.  Ammonic  carbonate.— (NH J ^003.  (Carbonate  of 
ammonia.  NH40,C02.)  —  This  should  be  completely 
volatilized  when  heated,  and,  after  supers aturation  with 
nitric  acid  and  heating,  should  give  no  reaction  with  solu- 
tions of  silver,  barium,  or  ammonic  sulphide.  Dissolve  it 
in  4  parts  of  water,  and  add  1  part  of  ammonia.  Keep 
some  of  the  salt  also  in  the  dry  form. 

c.  Ammonic  chloride. — ^XH.Cl.  (Chloride  of  ammo- 
nium.)— ^This  should  be  completely  volatilized  when  heated 
on  platinum  foil,  and  should  give  no  reaction  with  am- 
monic sulphide,  baric  chloride,  or  litmus.  Dissolve  in  8 
parts  of  water.  Keep  some  of  the  salt  also  in  the  form 
of  a  dry  powder. 

d  Ammonic  fluoride.— NH,F.  (Fluoride  of  ammonium.) 
— This,  when  heated  in  a  platinum  dish,  should  leave  no 
residue;  if  impure,  it  may  be  purified  by  sublimation 
between  two  platinum  dishes.  It  should  be  kept  in  gutta 
percha  bottles. 


§    3.       REAGKNTS.  11 

e.  Amnionic   hydrate.— NH^HO.    Ammoiia  JSTJff^.— 

This  should  be  colorless,  and  leave  no  residue  when  evap- 
orated in  a  watch-glass  :  after  dilution  with  its  volume  of 
water,  it  should  give  no  very  marked  turbidity  with  lime- 
water,  and,  after  supersaturation  with  nitric  acid  in  slight 
excess,  it  should  give  no  precipitate  or  color  with  argentic 
nitrate,  baric  chloride,  or  ammonic  sulphide. 

/.  Amnionic  molybdate.  —  (NHJ^MoO^.    (Molybdate 

of  ammonia.  KH^OjMoOg.) — Dissolve  1  part  of  molyb- 
dic  acid  in  8  parts  of  ammonia-water,  pour  the  solution 
into  20  parts  by  weight  of  nitric  acid  (Sp.  Gr.=1.2),  let 
the  mixture  stand  several  days  in  a  warm  place,  and 
decant  the  clear  liquid  for  use.  When  moderately  heated 
with  excess  of  nitric  acid,  it  should  give  no  yellow  pre- 
cipitate. 

g.  Ammonic  nitrate. — ISTH^lSrO,.  (Nitrate  of  ammonia. 
NH^O,  NO^.) — This  should  give  no  reaction  with  baric 
chloride  or  argentic  nitrate,  and  should  be  completely 
volatilized  when  heated. 

A.  Ammonic  oxalate. — (NHJ^C^O,.  (Oxalate  of  am- 
monia. 2X11^0,0^0^.) — This  should  be  completely  vola- 
tilized by  heat,  and  should  give  no  reaction  with  hydro- 
sulphuric  acid,  or  ammonic  sulphide,  or  with  baric  chloride 
in  a  solution  acidified  with  hydrochloric  acid.  Dissolve 
in  24  parts  of  water. 

i.  Ammonic  sulphate. — (NII,)„SO^.  (Sulphate  of  am- 
monia. NH^OjSOg.) — This  may  be  readily  prepared  by 
neutralizing  ammonic  hydrate  with  dilute  sulphuric  acid. 

Jc.  Ammonic  Sulphide. —  (NH,),S.  (Sulphide  of  am- 
monium. NH^S.) — Conduct  sulphuretted  hydrogen  (§  1, 
cl)  into  3  parts  of  ammonic  hydrate  as  long  as  the  gas 
is  absorbed,  and  add  2  parts  of  fresh  ammonic  hydrate. 
The  reagent  should  evolve  sulphuretted  hydrogen  freely 
when  mixed  with  strong  acids,  and  should  give  at  least 
only  a  white  precij)itate  with  them  ;  it  should  give  no  re- 


13.  §    4.       IlEAGEXTS. 

action  at  all  with  solutions  of  lime  or  magtiesia ;  when 
evaporated  in  a  platinum  dish,  the  residue  should  be  vola- 
tilized completely  on  ignition. 

-  Dissolve  some  flowers  of  sulphur  in  a  small  portion  of 
the  reagent,  and  label  this  solution,  ammonia  sulphide 
with  excess  of  sulphur, 

I  Ammonic  tartrate.— (N"HJ^  CJ-ip,.  (Tartrate  of 
ammonia.  2XH^O,CgIl40j„.)  —  Neutralize  tartaric  acid 
with  ammonic  hydrate,  and  then  add  more  ammonic  hy- 
drate, so  that  it  shall  be  in  excess  over  the  acid. 

m.  Ammonic-ferrons  sulphate.  —  (NHJ^Fc  (SOJ^. 
(Sulphate  of  j^rotoxide  of  iron  and  ammonia.  NH^O, 
FeO,  (SOg),.) — ^Divide  a  quantity  of  sulphuric  acid  into 
two  equal  parts ;  heat  one  of  them  with  an  excess  of 
small  clean  iron  nails  free  fi'om  rust,  as  long  as  the  evolu- 
tion of  hydrogen  continues.  Neutralize  the  other  portion 
of  the  acid  accurately  with  ammonic  carbonate,  and  then 
add  a  few  drops  of  sulphuric  acid,  Filter  the  solution  of 
ferrous  sulphate,  obtained  by  the  action  of  the  acid  on  the 
nails,  into  the  amnionic  sulphate,  evaporate  the  mixture 
a  little  if  necessary,  and  let  it  crystallize.  Let  the  crys- 
tals drain  in  a  funnel,  dry  them  by  exposure  to  the  air  0:1 
filter-paper,  and  keep  them  in  a  well  stoppered  bottle. 
The  solution  of  the  salt  in  water  acidified  with  sulpliuric 
acid  should  give  no  red  color  with  potassic  sulj^hocyanate. 

4.  Argentic  nitrate.  —  AgNO^.  (Nitrate  of  silver. 
AgO,  NO^.) — After  the  solution  of  this  reagent  has  been 
completely  precipitated  with  hydrochloric  acid,  the  fil- 
trate from  the  j)recipitate  should  leave  no  residue  Avlien 
evaporated,  and  the  same  filtrate  should  give  no  color 
with  ammonic  sulphide.     Dissolve  in  20  parts  of  water. 

All  the  silver  refuse,  consisting  of  precipitates  contain- 
ing silver,  and  solutions  to  which  argentic  nitrate  has  been 
added,  should  be  tlirown  into  a  bottle  containincr  dilute 
hvdrochloric  acid.     When    a  sufficient  quantity   of  the 


§    5.       IIEAGENTS.  13 

precipitated  chloride  has  accumulated,  separate  it  from 
the  liquid  by  decantation  of  the  latter,  wash  it  well  with 
water,  pour  diUite  sulphuric  acid  over  it,  and  put  some 
pieces  of  zinc  in  contact  witli  it. 

When  the  wliolo  is  changed  to  a  gray  metallic  powder, 
and  the  zinc  is  all  dissolved,  filter  out  and  wash  the  pow- 
der well,  dry,  and  ignite  it.  Dissolve  the  silver  thus  ob- 
tained in  nitric  acid,  add  water,  filter  if  necessary,  evap- 
orate the  filtrate  to  dryness  on  the  water-bath,  and  dis- 
solve the  residue  in  20  parts  of  water,  and  subject  the 
solution  to  the  tests  above  described. 

5.  c^— Baric  acetate.  —  Ba(C2H302)„.  Acetate  of 
baryta.  BaO,C JI3O3.  BaO,A.)— This  should  be  colorless 
and  should  have  no  empyreumatic  odor,  and  it  should 
give  no  reaction  with  amnionic  sulphide  or  argentic  ni- 
trate ;  after  complete  precipitation  witli  sulphuric  acid, 
the  filtrate  should  leave  no  residue  on  evaporation.  Dis- 
solve in  10  parts  of  water. 

h.  Baric  chloride. — BaCl^.  (Chloride  of  barium.  BaCl.) 
— This  should  not  afifcct  litmus-paper,  nor  give  any 
reaction  with  amraonic  sulphide ;  after  complete  pre- 
cipitation with  sulphuric  acid,  the  filtrate  from  the  precipi- 
tate should  leave  no  residue  when  evaporated.  Dissolve 
in  10  parts  of  water. 

c.  Baric  hydrate. —  Ba(HO)„.  (Hydrate  of  baryta. 
Baryta  water.  BaO,HO.)  —  After  precipitation  of  the 
barium  from  the  solution  by  sulphuric  acid,  the  filtrate 
should  remain  clear  when  mixed  with  alcohol,  and  should 
leave  no  residue  when  evaporated.  Dissolve  in  20  parts 
of  water.  In  determinations  of  urea  in  urine,  a  mixture 
of  one  volume  of  a  cold  saturated  solution  of  baric  nitrate 
and  two  volumes  of  a  cold  saturated  solution  of  baric 
hydrate  is  used. 

cl  Baric  nitrate.— BaCNO,),.  (titrate  of  baryta.  BaO, 
NO^.) — This  should   be  completely  precipitated  by  sul- 


14  §    G.       REAGENTS. 

phuric  acid  so  that  the  iiltrate  from  the  precipitate  leaves 
no  residue  when  evaporated,  and  it  should  give  no  reac- 
tion with  argentic  nitrate. 

€.  Calcic  chloride. — CaCl^.  (Chloride  of  calcium.  CaCl.) 
— This  should  not  affect  litmus-paper,  should  give  no 
reaction  with  ammonic  sulphide,  nor  any  ammonia  when 
heated  with  sodic  hydrate.  Dissolve  the  crystals  in  5 
parts  of  water. 

The  crude,  impure,  fused  chloride  answers  for  desicca- 
ting purposes. 

/.  Calcic  fluoride.— CaF^.  Fluor  spar. — To  cave 
trouble,  buy  the  powdered  fluor  sj^ar. 

g.  Calcic  hydrate.  — Ca(HO) 3.  Lime-water.  (CaO, 
HO.) — Digest  slaked  lime  with  cold  water  with  occasional 
stirring,  let  the  mixture  stand  quietly  for  a  time,  and  de- 
cant the  clear  liquid  for  use.  It  should  give  a  dark  color 
to  turmeric-paper,  and  a  considerable  precipitate  with 
ammonic  oxalate. 

For  many  purposes  milk  of  lime  is  used  in  preference 
to  lime-water  ;  this  reagent  is  simply  lime-water,  mixed 
with  an  excess  of  undissolved  calcic  hydrate.  It  should 
be  made  with  lime  from  white  marble,  and  should  be  kept 
in  well  stoppered  bottles,  and  shaken  up  Avhen  used. 

A.  Calcic  sulphate.— CaSO^.  (Sulphate  of  lime.  CaO, 
SO3.) — ^Digest  powdered,  crystallized  gypsum  a  long  time 
with  cold  water,  witli  frequent  agitation,  let  the  mixture 
stand  quietly  at  last,  and  decant  the  clear  liquid  for  use. 

6.  Chlorine. — CI. — Nearly  fill  a  flask  with  manganic 
binoxide  in  pieces  about  as  big  as  peas,  and  then  add  so 
much  common,  concentrated  hydrochloric  acid,  that  about 
half  the  oxide  will  be  immersed  in  it.  Conduct  the  gas, 
by  a  glass  tube  passing  through  the  cork  with  which  the 
mouth  of  the  flask  is  closed,  through  a  cylinder  or  wash- 
bottle  containing  concentrated  sulphuric  acid.     The  evo- 


^    7.       KEAGENTS.  15 

lution  of  tlic  chlorine  begins  at  common  temperatures,  but 
a  little  heat  must  be  applied  after  a  time. 

7.  Cobaltic  nitrate. — Co  (NO  J. _,,— Dissolve  the  salt  in 
10  parts  of  water. 

8.  Cochineal  solution* — Boil  cochineal  with  water. 
The  solution  will  keep  better  if  about  half  its  volume  of 
alcohol  is  added  to  it. 

9.  «.— Cupric  acetate.— Cu  (CJIgOJCuO.  (Acetate 
of  copper.  Verdigris.  2CuC),CJl303.) — To  prepare  the 
solution  of  this  salt  for  w^ashing  the  precipitate  of  baric 
sulphate,  dissolve  the  commercial  salt  in  water  contain- 
ing a  little  acetic  acid,  add  2  drops  of  sulphuric  acid,  if 
this  acid  is  not  already  present,  then  a  few  drops  of  baric 
chloride  until  the  liquid  gives  a  faint  reaction  for  barium, 
boil  a  short  time,  and  filter.  The  solution  should  be  suffi- 
ciently concentrated  to  deposit  crystals  on  cooling.  Use 
the  supernatant  saturated  solution. 

^.  Cupric  sulphate.  —  CuSO^.  (Sulphate  of  copper. 
CuO,S03.) — This  should  be  recrystallized  once  or  twice. 

10.  f  urcuma-paper.  — Turmeric-paper.  —  Digest  pul- 
verized curcuma  root  with  6  parts  of  weak  alcohol,  color 
slips  of  unsized  paper  with  the  yellow  extract,  and  dry 
them. 

11.  Ether.— C,H,„0.  (C,RO.)— Tliis  is  sufficiently 
pure  as  obtained  of  the  druggist. 

12.  a.— Ferric  chloride.— Fe^Clg  (Perchlorideofiron. 
Fe^Clg.) — Its  solution  should  give  a  permanent  precipi- 
tate with  a  drop  or  two  of  ammonic  hydrate ;  it  should 
give  no  blue  color  witli  potassic  ferricyanide.  Dissolve  in 
20  parts  of  water. 

b.  Ferric  oxide. — Fe.O.^.  (Sesquioxide  of  iron.) — This 
is  also  known  as  colcothar. 

c.  Ferric  nitrate.— Fe(N03) 3.  (Nitrate  of  sesquiox- 
ide of  iron.     Fe,0 3,31^0 ^.)— Dissolve  iron  in  nitric  acid, 


16  §    13.       IlEAGENTS. 

evaporate  the   solution  to  expel  excess  of  acid,  and  dis- 
solve the  residue  in  10  parts  of  water. 

d.  Ferrous  chloride. — FeCl^.  (Protocliloride  of  iron. 
FeCl.) — Dissolve  j)ianoforte  wire  in  concentrated  hydro- 
chloric acid ;  the  solution  should  be  made  as  it  is  wanted. 

6.  Ferrous  sulphide.— FeS.  (Sulphide  of  iron,)— Get 
the  fused  sulphide  of  the  druggists. 

13*  Hydrogen. — H. — This  is  made  by  the  action  of  di- 
lute sulphuric  acid  on  granulated  zinc.  To  purify  the  gas 
conduct  it  through  a  TJ  tube,  or  a  calcic-chloride  cylinder, 
containing  freshly  ignited  charcoal,  and  in  order  to  dry 
it,  through  another  cylinder  containing  calcic  chloride. 

14.  Indigo  solution. — This  may  be  prepared  by  treat- 
ing 1  part  of  finely  powdered  indigo  with  5  parts  of 
fuming  sulphuric  acid  48  hours  in  the  cold,  and  pouring 
the  mixture  into  20  parts  of  cold  water. 

15.  Iodine. — I. — This  needs  no  testing. 

16.  a. — Iron  Turnings. — These  should  be  clean  and 
free  from  grease. 

h.  Iron  wire. — Get  the  finest  pianoforte  wire,  free  from 
inist. 

17.  a. — Lead-paper. — Soak  slips  of  unsized  paper  in  a 
solution  of  plumbic  acetate,  dry,  and  keep  in  a  well  stop- 
i^ered  bottle. 

h.  Litmus-paper  (blue). — Digest  litmus  with  G  parts  of 
water,  filter,  divide  half  of  the  filtrate  into  two  equal 
parts  and  carefully  saturate  the  free  alkali  in  one  of  these 
parts  with  sulphuric  acid,  until  the  liquid  has  taken  a  red 
color  that  docs  not  disappear  after  standing  a  few  min- 
utes ;  add  the  other  part  to  this,  color  strips  of  unsized 
paper  in  the  blue  liquid,  dry  them,  and  keep  in  a  dark 
place.     The  strips  should  have  a  blue  color. 

c.  Litmus-paper  (red). — Add  sulphuric  acid  to  the 
other  half  of  the  extract  of  the  litmus  until  a  permanent 


§    18.       HE  AGENTS.  17 

red  color  is  just  obtained  ;  color 'slips  of  unsized  paper  in 
this  solution,  dry  them,  and  keep  in  a  dark  place.  The 
strips  should  have  a  distinct  red  color. 

18.  a. — Magnesia  (calcined).— MgO. — This  should  be 
freshly  ignited  before  being  used. 

h.  Magnesia  mixture. — ^Mix  together  1  part  of  mng- 
nesic  sulphate,  MgSO^,  1  of  amnionic  .-chloride,  4  of  am- 
monic  hydrate,  and  8  of  water;  let  the  mixture  stand 
several  days  in  a  moderately  warm  j)lace,  and  decant  the 
clear  solution  for  use. 

19t  Malt. — Get  good  brewer's  malt. 

20.  Manganic  binoxide. — MnO„. — The  commercial,  na- 
tive, crystallized  hmoxide  of  manganese  is  generally  suf- 
ficiently pure. 

21.  a.— Mercuric   nitrate.— Hg (NO 3)^.    (Nitrate  of 

mercury.  HgO,N05.)  —  Dissolve  mercury  in  its  own 
w^eight  of  nitric  acid  (Sp.  Gr.=1.4),  heat  the  mixture  to- 
wards the  close  of  the  operation,  and,  finally,  add  to  it 
twice  its  bulk  of  water. 

h,  Mercurous  nitrate.— Hg2(N03)2. — (Subnitratc  of 
mercury.  Hg^O,  NO^.) — Pour  1  part  of  pure  nitric  acid 
(Sp.  Gr.=1.2)  over  1  part  of  mercury,  let  stand  24  hours 
in  a  cool  place,  separate  the  crystals  from  the  undissolved 
mercury  and  the  mother-liquor,  dissolve  them  in  water 
mixed  with  ^1^^  of  nitric  acid,  by  trituration  in  a  mortar, 
filter,  and  keep  the  solution  in  a  bottle  with  metallic  mer- 
cury covering  the  bottom. 

MicroCOSmic  salt. — ^qqsocHg  ammonic phospJiate. 

Milk  of  lime. — See  calcic  hydrate. 

22*  Oxygen. — O. — Mix  together  in  a  mortar  100  grms. 
of  potassic  chlorate  and  0.1  grm.  of  ferric  oxide,  half  fill 
a  retort  with  the  mixture,  and  heat  over  a  coal  fire,  at  first 
gently.  As  soon  as  the  contents  of  the  retort  are  partly 
fused,  mix  them  together  by  gentle  iagitation.     Collect 


18  §    23.       KE  AGENTS. 

the  gas  in  the  gasometer ;  for  use,  conduct  it  from  the 
gasometer  through  a  solution  of  caustic  potash  (Sp.  Gr.= 
1.27)  in  a  Liebig's  potassa-bulb,  then  through  a  U  tube 
containing  pumice-stone  soaked  in  sulphuric  acid,  and 
finally  through  a  tube  containing  calcic  chloride. 

Phosphorus  salt. — See  sodic  ammonic  phosphate. 

23.  Platinic  chloride.— PtCl^.  (Bichloride  of  plat- 
inum. PtCl^.) — Its  solution,  evaporated  to  dryness  on 
the  water-bath,  should  leave  a  residue  entirely  soluble  in 
alcohol. 

Precipitates  and  solutions  containing  platinum  should 
be  thrown  into  a  bottle  containing  a  solution  of  ammonic 
chloride.  When  a  sufficient  quantity  of  the  precipitate 
has  accumulated,  separate  it  from  the  liquid  by  filtration, 
wash,  dry,  and  ignite  it  strongly.  Exhaust  the  residue 
thoroughly  with  hot  nitric  acid,  wash  the  insoluble  part 
in  water,  dissolve  in  aqua  regia  with  the  aid  of  a  gentle 
heat,  adding  fresh  portions  of  nitric  acid  until  the  plat- 
inum is  completely  dissolved,  evaporate  the  solution  on 
the  water-bath,  with  the  addition  of  hydrochloric  acid, 
and  dissolve  the  semi-fluid  residue  in  10  parts  of  water. 

24.  a.— Plumbic  acetate.— Pb  (CJIgOJ^.  (Acetate 
of  lead.  PbO,  C.JI3O3.  PbOA.)— The  basic  acetate, 
Ph  {CJI^O^„  2  PbO,  is  prepared  by  treating  120  grms. 
of  crystallized  common  acetate  (sugar  of  lead)  with  60 
grms.  of  gently  ignited,  and  then  finely  pulverized  plumbic 
oxide  (litharge),  and  400  c.c.  of  water ;  let  the  mixture 
stand  some  time  in  a  Avarm  place  with  frequent  agitation, 
and  finally  filter  the  liquid  for  use. 

b.  Plumbic  binoxide. — PbO^. 

e.  Plumbic  oxide. — PbO.     IJtharge. 

25.  a. — Potassic  acetate. — KC^HjO,.  (Acetate  of  po- 
tassa.  KO,C^H303.) — This  should  be  white  and  free  from 
cmpyreumatic  odor.     Dissolve  in  5  parts  of  water. 


§    25.       IIEAGEXTS.  •  10 

h.  PotaSSic  bisulphate.— KHSO^.  (Bisulphate  of  po- 
tasga.     K0,H0,S03.) 

0.  Potassic  chromate. — ^K^CrO^.  (Chromate  of  po- 
tassa.  KOjCrOg.) — This  should  give  no  turbidity  with 
argentic  nitrate,  after  acidification  with  nitric  acid.  Make 
a  cold  saturated  solution. 

d.  Potassic  chlorate. — KCIO^.  (Chlorate  of  potassa. 
K0,C10,.) 

e.  Potassic  dicliromate. — K^Cr^O,.  (Bichromate  of 
potassa.  KO,2Cr03.) — This  should  be  recrystallized. 
Dissolve  it  in  12  parts  of  water. 

/.  Potassic  fcrricyanide.— K3Cy,re.  K3Cfdy.  (Fer- 
ricyanide  of  potassium.  K3Cy,Fe2.) — This  should  give 
no  blue  color  with  ferric  chloride. 

g.  Potassic  ferrocyanide.— K^Cy^Fe.  K.Cfy.  (Fer- 
rocyanide  of  potassium.  K2Cy3Fe.) — Dissolve  in  12  parts 
of  water. 

h.  Potassic  hydrate.— KHO.  (Potassa  KO,HO.)— 
This  should  not  be  changed  by  ammonic  sulphydrate,  and 
should  efiervesce  but  slightly  if  at  all  with  hydrochloric  acid; 
the  solution  obtained  with  hydrochloric  acid  in  excess, 
when  evaporated  to  dryness  should  give  a  residue  that  is 
at  least  almost  completely  dissolved  by  water ;  the  same 
solution  should  give,  at  the  most,  but  a  very  slight  reac- 
tion for  i^hosphoric  acid  with  ammonic  molybdate,  and 
should  give  but  a  slight  flocculent  precipitate  with  am- 
monia in  excess,  after  long  standing  in  a  warm  place. 
Pure  potassa  prepared  from  an  alchoholic  solution  of  the 
hydrate  should  give  none  of  these  reactions.  Dissolve  in 
10  parts  of  water. 

i,  Potassic  iodide. — KT.  (Iodide  of  potassium.) — This 
is  sufficiently  pure  as  obtained  from  the  druggists. 

Jc.  Potassic  permanganate.  — K^Mn^Og.  (Perman- 
ganate of  potassa.     KOjMn^O,.) 


20  '  §    26.       REAGENTS. 

/.  Potassic  sodic  carbonate. — KNaCOg.  (Carbonate 
of  potassa  and  soda.  KO,  NaO,  2  CO^.) — Recrystallize 
some  potassic  sodic  tartrate,  ignite  the  salt  in  a  silver 
dish  until  completely  charred,  exhaust  the  black  residue 
with  water,  filter,  evaporate  the  filtrate  to  dryness  in  the 
silver  dish,  and  keep  the  salt  in  a  well  stoppered  bottle ; 
when  it  is  fused  with  a  little  pure  sodic  nitrate,  and  the 
residue  is  dissolved  in  water  and  nitric  acid,  and  then  am- 
monia added,  each  in  slight  excess,  no  flocculent  precipi- 
tate should  appear  after  long  standing  in  a  warm  place. 

m.  Potassic  sodic  tartrate.— KNaC^H.O^.  (Seign- 
ette  salt.  Tartrate  of  potassa  and  soda.  KO,  NaO, 
CgH^O,^.) — This  should  be  recrystallized  once  or  twice. 
It  should  give  a  colorless  solution  with  water. 

71.  Potassic  SUlpllOCyanate.—KCyS.  (Sulphocyanide 
of  potassium.      KCy  S„.) — Dissolve  in  20  parts  of  water. 

26.  Quartz,  powdered, — SiO„. — Drench  red-hot  quartz 
with  cold  water,  and  reduce  the  friable  mass  to  a  very 
fine  powder. 

27.  a. — Soda  lime. — Na^CaO^. — This  should  not  effer- 
vesce much  with  acid,  and,  Mhen  mixed  with  pure  sugar 
and  heated  to  redness,  it  should  evolve  no  ammonia. 

In  order  to  have  the  reagent  perfectly  free  from  nitro- 
gen, Lawes  and  Gilbert  found  it  necessary  to  mix  it 
intimately  with  1-2  "1^  of  sugar  or  some  other  non- 
nitrogenous  substance,  and  ignite  the  mixture  in  a  muffle, 
then  to  moisten  it,  and  heat  it  again  gently. 

h.  Sodic  acetate. — NaC^HgO^.  (Acetate  of  soda. 
NaO,  CJI3O3.) — This  should  be  colorless  and  have  no 
empyreumatic  odor,  and  should  give  no  reaction  with 
ammonic  molybdate  or  baric  chloride.  Dissolve  in  10 
parts  of  Avater. 

e.  Sodic  ammonic  phosphate.— NaNHJIPO,  Phos- 
phorus salt.     (Phosphate  of  soda  and  ammonia.     NaO, 


§    28.       IIEAGENTS.  21 

KHp,HO,  PO^.)— This  should,  give  a  colorless  bead  when 
fused  on  platinum  wire. 

d.  Sodic  bisulphite.— HNaS03.  (Bisulphite  of  soda. 
NaOjHOjSO,.) — This  should  give  a  residue  Avhen  heated 
with  sulphuric  acid,  whose  solution  is  not  changed  by 
hydrosulphuric  acid  or  amnionic  molybdate.  Dissolve  in 
10  parts  of  water. 

e.  Sodic  carbonate. — lNra2C03.  (Carbonate  of  soda. 
KaOjCOjj.)- — This  should  be  perfectly  white,  and  the  solu- 
tion obtained  after  supersaturation  with  nitric  acid  should 
give  no  precipitate  nor  color  with  baric  chloride,  argentic 
nitrate,  or  potassic  sulphocyanate,  nor  any  reaction  with 
ammonic  molybdate,  nor  any  insoluble  residue  of  silicic 
acid  w^hen  evaporated  to  dryness.  Dissolve  the  crystal- 
lized salt  in  3  parts  of  water,  or  the  anhydrous  salt  in  5 
parts.     Keep  some  of  the  ignited  salt  in  the  dry  form. 

/.  Sodic  hyposulphite.— ^a.SJI^O^.  (Hyposulphite 
of  soda.     N"aO,HO,S,0,.) 

g*  Hydric  di  sodic  phosphate. — Xa^HPO^.  (Phosphate 
of'  soda.  2]SraO,IIO,PO^.)— This  should  not  be  made 
turbid  Avhen  heated  with  ammonia,  and  the  precipitate 
produced  by  argentic  nitrate,  or  baric  chloride,  should  be 
dissolved  completely  and  without  effervescence  by  dilute 
nitric  acid.     Dissolve  in  10  parts  of  water. 

Ji,  Sodic  nitrate. — NaNO^.  (Nitrate  of  soda.  KaO", 
KO^.) — This  should  give  no  reaction  with  argentic  nitrate 
or  baric  chloride,  nor  with  sodic  carbonate. 

28.  Starch-paper. — Boil  starch  with  25  parts  of  water, 
saturate  strips  of  paper  with  the  liquid,  and  dry  them. 

Tannin. — See  acid^  tannic. 

29.  Tin.— Sn.— Get  the  best  tinfoil  of  the  druggists, 
or  pure  tin  in  small  sticks. 

Turmeric-paper. — See  curcuma-paper. 

30.  Uranic  acetate.  —  (U,0)  C,H30,.     (Acetate  of 


22  §    31'       llEAGENTS. 

uranium.  (JJfi^fiJIfi^.) — Heat  uranic  nitrate  until  a 
small  part  of  the  uranic  oxide  is  reduced,  digest  the 
yellowish-red  residue  with  acetic  acid,  filter  the  liquid 
and  set  the  filtrate  aside  to  crystallize ;  the  crystals  are 
composed  of  uranic  acetate,  while  uranic  nitrate  remains 
in  solution. 

The  solution  of  the  acetate  should  not  be  changed  by 
sulphuretted  hydrogen  after  acidification  with  hydrochlo- 
ric acid,  and  should  give  a  precipitate  with  ammonic  car- 
bonate that  is  entirely  soluble  in  an  excess  of  the  reagent. 

31.  Urea. — Recrystallize  it  from  its  solution  in  alcohol. 

32.  Water,  distilled. — H^O.— This  can  be  prepared  by 
the  analyst  himself,  if  necessary.  Dealers  in  apparatus 
can  supply  small  stills  of  copper  and  worms  of  block-tin, 
put  together  and  ready  for  use.  The  water*  must  be 
colorless  and  tasteless,  and  it  should  leave  no  residue 
when  evaporated  in  a  platinum  dish.  Ammonic  sulphide 
should  give  no  color  to  it,  nor  should  basic  plumbic  ace- 
tate make  it  turbid,  nor  should  ammonic  oxalate  or 
argentic  nitrate  make  it  turbid  after  long  standing. 

33.  Zinc. — Zn. — This  should  give  no  reaction  for  arsenic 
with  Marsh's  test,  and,  wlien  dissolved  in  nitric  acid  with 
the  aid  of  heat,  it  should  give  no  red  color  with  potassic 
sulphocyanate.  Fresenius  recommends  that  before  using 
zinc  for  reducing  ferric  to  ferrous  oxide  in  the  estimation 
of  iron  by  the  permanganate  process,  it  should  be  tested 
by  the  same  process.  Dissolve  a  piece  of  the  zinc  in  di- 
lute sulphuric  acid  in  the  small,  long-necked  flask,  as  de- 
scribed in  §  52,  5,  and,  after  the  flask  is  filled  with  water 
and  its  contents  are  cold,  add  a  drop  of  a  very  dilute  so- 
lution of  potassic  permanganate,  and  at  the  same  time 
add  another  drop  to  the  same  volume  of  pure  water,  and 
stir  both  mixtures  well.  The  depth  of  color  communica- 
ted to  both  liquids  should  be  precisely  the  same. 


§    34.      DETEEMINATION    OF   SPECIFIC   GRAVITY.         23 

CHAPTER    II. 

ANALYTICAL    MANIPULATION. 

Determination  of  Specific  Gravity. 

34.  By  the  specific  gravity  of  a  solid  or  Jiquid  is  un- 
derstood its  weight  as  compared  with  the  weight  of  an 
equal  volume  of  water. 

a.  The  most  obvious  method  of  determining  it  is  to 
weigh  equal  volumes  of  the  substance  and  of  water.  This 
is  easily  accomplished  in  the  case  of  liquids,  with  the  aid 
of  the  so-called  specific-gravity  bottle  or  piknometer,  an 
instrument  made  of  thin  glass  and  provided  with  an  ac- 
curately ground  stopper ;  the  stopper  is  sometimes  per- 
forated. The  weight  of  the  empty  bottle  is  ascertained, 
then  its  weight  when  completely  filled  with  water,  or 
filled  to  a  mark  on  the  neck,  and  finally  when  filled  to 
the  same  extent  with  the  liquid  under  examination ;  be- 
fore weighing,  in  each  case,  all  adhering  particles  of  liquid 
should  be  carefully  wiped  off  with  blotting  paper ;  both 
weighings  should  be  made  at  as  nearly  the  same  tempera- 
ture as  possible,  or  at  about  15°  C.,the  usual  temperature 
of  the  working  room.  Divide  the  weight  of  the  liquid 
by  that  of  the  water^for  the  specific  gravity  of  the  former. 

h  The  specific  gravity  of  liquids  is  also  determined 
with  great  facility,  though  with  less  accuracy,  by  means 
of  the  areometer  or  hydrometer;  this  is  a  glass  tube 
closed  at  both  ends,  considerably  enlarged  towards  one 
end,  and  loaded  with  mercury  to  make  it  take  a  vertical 
position  in  the  liquid,  but  not  with  enough  to  cause  it  to 
sink  under  the  surface.  The  use  of  the  areometer  depends 
upon  the  principle,  that  the  less  the  specific  gravity  of  a 
liquid  is,  the  less  its  buoyant  power.     The  specific  gravi- 


a4  §    35.       ANALYTICAL   MANIPULATION. 

ties  corresponding  to  the  diiferent  depths  to  which  the  in- 
strument will  sink  in  liquids  of  different  densities,  are 
marked  on  a  scale  in  the  upper,  slender  part  of  the  tube. 
The  temperature  of  the  liquid  whose  specific  gravity  is  to 
be  determined  with  the  hydrometer  should  be  as  nearly 
15°  C.  as  possible. 

(?.  As  there  is  a  fixed  relation  between  the  degree  of 
concentration  and  the  specific  gravity  of  a  solution  of 
any  given  substance,  areometers  are  constructed,  upon 
whose  scales  the  amount  of  the  substance  in  100  parts  of 
its  solution  is  given,  instead  of  the  specific  gravity  of  a 
solution  of  that  j^articular  degree  of  concentration.  Thus, 
we  have  alcoholometers  for  mixtures  of  alcohol  and  water, 
saccharometers  for  solutions  of  sugar,  acetometers  for  so- 
lutions of  acetic  acid,  lactometers  for  milk. 

35.  a. — To  determine  the  specific  gravity  of  a  solid^  we 
may  Aveigh  it  first  in  the  air,  and  then  while  immersed  in 
w^ater,  and  suspended  from  the  arm  of  the  balance  by  a 
fine  thread  or  hair.  The  difference  between  these  two 
weights,  divided  into  the  Aveight  of  the  body  in  the  air, 
will  give  its  specific  gravity. 

h.  Or,  if  the  substance  is  in  the  form  of  a  powder  that 
is  insoluble  in  water,  we  may  weigh  it  first  by  itself  in 
the  specific-gravity  bottle,  then  fill  the  bottle  with  water, 
as  in  §  34,  r/,  and  weigh  again.  The  difierence  between 
the  weights  of  Avater  that  the  bottl^  Avill  hold,  with  and 
without  the  substance  in  it,  Avhich  is  the  Aveight  of  a  a'oI- 
ume  of  water  equal  to  that  of  the  solid  substance,  divided 
into  the  weight  of  the  substance  itself,  Avill  give  its  spe- 
cific gravity. 

c.  Or,  taking  advantage  of  the  fact  that  a  cubic  centi- 
inetre  of  water  weighs  very  nearly  one  gramme  at  com- 
mon temperatures,  we  may  make  a  rough  determination 
of  the  specific  gravity  by  filling  a  500  c.c.  graduated  cyl- 
inder exactly  up  to  the  250  c.c.  mark,  then  putting  a 


§   36.      SOLUTION.  25 

weighed  quantity  of  the  substance  (100  or  200  grms.)  in 
the  cylinder,  shaking  the  mixture  well  so  as  to  disengage 
bubbles  of  air,  and  observing  the  volume  occupied  by 
both  the  substance  and  the  water ;  the  increased  volume, 
which  represents  that  of  the  substance  added,  expressed 
in  cubic  centimetres,  divided  into  the  weiglit  of  the  sub- 
stance taken,  expressed  in  grammes,  will  nearly  equal  the 
specific  gravity. 

d.  If  the  substance  is  soluble  in  water,  some  other  liquid, 
like  alcohol  or  naptha,  must  be  used.  Determine  the 
specific  gravity  of  the  substance  with  reference  to  this 
liquid,  by  the  same  rules  as  above,  and  then  multiply  the 
result  by  the  specific  gravity  of  the  liquid  used,  with  ref- 
erence to  the  common  standard,  water ;  the  product  will 
be  the  specific  gravity  of  the  substance  with  reference  to 
the  same  standard. 

e.  The  specific  gravity  of  a  substance  may  be  deter- 
mined roughly,  but  very  expeditiously,  as,  for  example, 
of  potatoes,  by  putting  several  samples  in  a  shallow  dish 
containing  a  saturated  solution  of  common  salt,  and  add- 
ing water  with  constant  stirring,  until  the  buoyant  power 
of  the  liquid  is  diminished  to  such  a  degree  that  half  the 
samples  swim  at  the  surface,  and  half  sink  to  the  bottom; 
it  can  then  be  assumed,  with  sufficient  accuracy  for  some 
purposes,  that  the  average  specific  gravity  of  the  article 
under  examination  is  the  same  as  that  of  the  solution, 
and  this  can  be  determined  with  the  aid  of  the  hydrome- 
ter (§  34,  h). 

SOLUTION. 

36.  In  order  that  a  substance  may  bo  analyzed  accord- 
ing to  the  methods  described  in  the  following  pages,  it 
must  be  brought  into  solution  if  not  already  dissolved. 
The  solvents  most  commonly  used  are  water,  hydrochloric 
acid,  and  nitric  acid,  for  inorganic  substances,  and  water, 
2 


26  §    36.      ANALYTICAL   MANIPULATION. 

alcohol,  and  ether,  for  organic  matters.  As  tlie  manner  of 
making  the  solntion  is  described  in  each  case,  when  spe- 
cial directions  are  necessary,  but  little  need  be  said  on  the 
subject  here.  As  a  general  rule,  heat  increases  the  sol- 
vent power  of  the  dissolving  agents  to  a  considerable  ex- 
tent, and  hence  it  should  always  be  applied,  unless  the 
solution  is  very  easily  accomplished  without,  or  unless  di- 
rections are  given  to  the  contrary.  Time  is  often  an  im- 
portant element  in  effecting  solution,  and  hence  long  con- 
tinued digestion  at  a  moderately  high  temperature  may 
be  useful,  or  even  necessary.  A  great  excess  of  strong 
acid  in  a  solution  to  be  analyzed  often  causes  much 
trouble ;  hence,  as  little  acid  as  possible  should  be  used, 
and  in  case  a  large  quantity  has  been  added  to  the  sub- 
stance, it  should,  in  most  cases,  be  removed  subsequently 
by  evaporation  almost  to  dryness. 

Unless  a  substance  is  readily  and  completely  soluble,  it 
is  essential  that  it  should  be  as  finely  divided  as  j^ossible, 
and,  to  this  end,  it  should  be  ground  to  a  fine  powder  in 
a  porcelain  mortar,  or,  better  still,  an  agate  one. 

In  order  to  reduce  a  substance  to  a  sufficiently  fine 
powder,  it  is  sometimes  necessary  to  levigate  it,  which 
means  simply  to  grind  it  in  the  agate  mortar  with  the 
addition  of  water  enough  to  make  a  thin  paste,  until  no 
grittiness  can  be  felt  under  the  pestle,  nor  any  grating 
sound  heard.  Then  rinse  the  contents  of  the  mortar 
into  an  evaporating  dish,  dry  the  substance  thoroughly 
over  the  water-bath,  and  mix  the  dry  residue  together 
carefully  by  further  gi-inding  in  the  mortar. 

In  making  a  solution  for  qtiantitative  purposes,  when 
the  loss  of  even  a  minute  part  of  the  substance  would 
impair  the  accuracy  of  the  results  obtained,  if  the  mixture 
of  substance  and  solvent  is  to  be  boiled,  or  if  the  sub- 
stance is  a  carbonate,  and  is  to  be  treated  with  an  acid,  it 
is  best  to  operate  in  a  flask  placed  on  its  side,  or  with  its 
mouth  loosely  stoppered  by  a  small  funnel,  or  in  a  beaker 


§    37.       EVAPORATION.  27 

covered  with  one  of  the  large  watch-glasses  now  so  much 
used  for  this  purpose.  The  flask  with  the  funnel  in  its 
mouth  is  better  for  the  solution  of  carbonates,  since  fresh 
quantities  of  acid  can  be  conveniently  added  from  time  to 
time.  When  the  solution  is  finished,  carefully  rinse  the 
funnel  or  watch-glass  into  the  flask  or  beaker. 

Heat  is  most  conveniently  applied  to  a  mixture  of  sub- 
stance and  solvent  with  the  aid  of  the  water-bath,  or  sand- 
bath,  in  making  solutions  for  quantitative  purposes,  and 
often  in  qualitative  analysis  also.  When  it  is  necessary 
to  boil  the  mixture  of  substance  and  solvent  for  a  consid- 
erable time,  and  the  solvent  is  more  or  less  volatile,  it 
is  best  to  connect  the  flask  with  the  loii^er  end  of  a  Lieb- 
ig's  condenser ;  the  vapor  of  the  liquid  as  it  is  condensed' 
flows  back  into  the  flask,  and  it  is  unnecessary  to  renew 
the  solvent  until  it  is  quite  saturated.     See  §  39,  c. 

EVAPORATION. 

37 •  A  liquid  may  be  evaporated  either  to  get  rid  of  a 
superabundance  of  water,  that  makes  the  solution  too  di- 
lute, or  to  expel  an  excess  of  acid,  or  for  the  purpose  of 
weighing  what  it  has  in  solution.  In  the  first  and  second 
cases,  the  operation  may  be  performed  in  porcelain  dishes, 
unless  the  solution  is  strongly  alkaline. 

a.  In  the  third  case,  if  the  quantity  of  the  liquid  is 
large,  it  may  be  evaporated  to  a  small  bulk  in  a  porcelain 
dish,  and  then  carefully  transferred  to  a  platinum  dish  or 
crucible.  Or  the  original  solution  may  be  put  into  the 
platinum  dish  in  small  quantities  at  a  time ;  if,  however, 
the  solution  contains  free  chlorine,  or  nitric  and  hydro- 
cldoric  acids  together,  it  must  be  evaporated  in  a  porcelain 
dish  until  no  more  fumes  of  chlorine  are  evolved ;  the 
residue  may  then  be  transferred  to  the  platinum  vessel, 
and  the  evaporation  continued. 

When  a  cpnsiderable  quantity  of  a  liquid  is  to  be  evap- 


28  §    37.       ANALYTICAL    MANIPULATION. 

orated,  the  operation  may  be  performed  at  first  directly 
over  the  lamp ;  but  in  quantitative  work  the  evaporation 
should  be  completed  on  the  water-bath  in  all  cases  ;  if  the 
original  quantity  of  the  solution  is  small,  it  is  better  to 
conduct  the  whole  evaporation  on  the  water-batli. 

If  the  evaporation  is  connected  with  quantitative  Avork, 
the  dish  should  never  be  more  than  three-fourths  filled, 
and  the  solution  should  not  be  allowed  to  boil  at  any  time 
i»  an  open  vessel;  evaporation  will,  however,  proceed 
quite  rapidly  in  a  flask  placed  partly  on  its  side,  and  in 
this  case  gentle  boiling  may  be  allowed. 

Unless  the  evaporation  is  performed  in  a  room  set  apart 
for  the  work,  and  entirely  free  from  dust,  solutions  should 
be  kept  covered  with  filter-paper  during  the  operation ; 
the  pnper  should  be  supported  by  glass  rods,  or  a  glass 
triangle,  laid  over  the  dish  in  such  a  manner  that  it  cannot 
como  in  contact  with  the  liquid  ;  if  the  solution  is  strong- 
ly acid,  the  paper  should  have  been  well  washed  with 
acid,  as  directed  for  washing  fdters  §  39,  a  ;  otherwise, 
drops  of  acid,  that  have  condensed  on  the  glass  rods 
and  come  in  contact  with  the  paper,  may  fall  back  into 
the  liquid  and  carry  with  them  inorganic  substances  that 
were  dissolved  out  of  tlic  paper. 

To  prevent  the  salts  in  solution  from  being  deposited 
on  the  sides  of  the  dish  above  the  liquid,  and  even  over 
the  edge,  smear  the  rim  of  the  dish,  just  below  the  edge 
on  the  inside,  with  the  thinnest  possible  coat  of  tallow. 
Or,  fit  the  dish  in  a  little  jacket  of  fire-clay,  in  such  a 
manner  that  the  part  of  it  above  the  liquid  shall  be  kept 
very  hot.  Or,  turn  the  crucible  on  its  side,  and  apply 
the  flame  of  the  lamp  just  above  the  surface  of  the  liquid. 

h.  When,  as  is  often  tlie  case  in  agricultural  analysis, 
potassa  or  soda  is  to  bo  estimated  in  a  solution  containing 
a  large  quantity  of  anunoniacal  salts,  and  from  which 
these  salts  are  to  be  removed  by  evaporation  to  dryness 
and  ignition,  Fresenius  recommends  to  evaporate  the  so- 


§    38.      PRECIPITATION.  29 

lution  to  dryness  in  a  porcelain  dish  on  the  water-bath, 
dry  the  residue  thoroughly  at  a  temperature  a  little  above 
100°  C,  transfer  it  to  another  dish  with  the  aid  of  a 
spatula,  rinse  the  porcelain  dish  with  a  little  water  into 
the  crucible  in  which  tlie  residue  is  to  be  finally  ignited, 
evaporate  these  washings  to  dryness,  then  ignite  the  dry 
residue,  obtained  above,  in  small  portions  at  a  time,  and 
finally  rinse  the  dish  that  contained  it  into  the  crucible, 
with  the  aid  of  a  little  finely  powdered  ammonic  chloride, 
and  ignite  again.  The  dish  with  the  residue  should  be 
kept  in  the  desiccator  while  waiting  for  the  ignition. 

PRECIPITATION. 

38t  Precipitation  is  usually  resorted  to  in  order  to  sep- 
.arate  certain  substances  from  others  in  the  same  solution, 
or  simply  from  the  solution  itself;  it  consists  in  adding 
some  reagent  to  the  solution,  which  causes  the  substance 
or  substances  in  question  to  enter  into  an  insoluble  form. 
The  operation  is  usually  performed  in  beakers,  because, 
from  these,  the  i:>recipitate  is  more  easily  transferred  to 
the  filter. 

Care  must  be  taken  not  to  use  too  large  an  excess  of 
the  precipitant,  and  yet  there  must  be  no  doubt  at  all  that 
enough  has  been  added  ;  if  the  precipitate  does  not  settle 
speedily,  so  that  the  efiect  of  the  addition  of  a  fcAV  more 
drops  of  the  reagent  can  be  observed,  a  small  portion  of 
the  mixture  should  be  throw^n  on  the  same  filter  that  is 
finally  to  receive  the  whole  of  the  j^recipitate,  and  the 
necessary  test  can  be  applied  to  the  filtrate ;  this  small 
portion  that  has  been  separated  from  the  main  part  of  the 
liquid  should  then  be  mixed  with  it  again,  before  more  of 
the  precipitant  is  added. 

The  solution  and  the  reagent  should  always  be  well 
mixed  by  stirring,  and,  in  most  cases,  the  solution  should 
be  so  dilute  that,  when  the  precipitate  settles,  it  will  not 


30  §    38.       AXALYTICAL   MANIPULATIOX. 

occupy  more  than  one-third  or  one-fourth  the  space  taken 
up  by  the  liquid  above  it ;  and,  moreover,  for  convenience 
in  filtration,  the  beaker  should  not  be  more  than  two- 
thirds  or  three-fourths  filled  by  the  mixture. 

A  few  precipitates  may  be  filtered  out  at  once,  in  quan- 
titative analysis,  but  in  most  cases  digestion  in  a  warm 
2:)]ace  for  a  longer  or  shorter  time,  is  required.  The  beak- 
er should  be  carefully  covered  during  the  digestion,  so 
that  no  particle  of  dust  can  get  in,  and  the  operation  is 
most  conveniently  performed  on  the  sand-bath. 

When  about  to  transfer  the  contents  of  the  beaker  to 
the  filter,  smear  a  very  little  tallow  under  the  lip  of  the 
former,  wet  a  glass  rod  in  the  liquid,  and  hold  tiiis  wet 
rod  against  the  lip  of  the  beaker  in  such  a  manner  that 
the  liquid  will  run  down  the  rod  and  against  one  side  of 
the  filter. 

Of  course  every  particle  of  the  precipitate  must  be 
transferred  to  the  filter  if  the  two  are  to  be  weighed 
together,  with  or  without  ignition.  Most  of  the  preci- 
pitate can  be  rinsed  out  of  the  beaker  by  means  of 
the  jet  from  the  washing-bottle ;  if  any  particles  re- 
main adhering  to  the  glass,  they  may  be  loosened  w^ith 
a  stiff  feather ;  or,  when  the  precipitate  is  to  be  ignited 
before  being  weighed,  a  quarter  or  a  half  of  a  filter,  of 
the  same  size  and  kind  as  that  in  the  funnel,  may 
be  moistened  slightly  and  rubbed  over  the  sides  and  bot- 
tom of  the  beaker  with  the  aid  of  the  glass  rod,  or  of 
glass-pointed  pincettes,  and  then  transferred  to  the  filter, 
with  most  of  the  remainder  of  the  precipitate  adhering 
to  it ;  a  little  subsequent  rinsing  with  the  Avash-bottle 
will  leave  the  beaker  thoroughly  cleansed ;  or  the  precipi- 
tate that  adheres  obstinately  to  the  sides  of  the  beaker 
may  be  dissolved  in  very  dilute  acid,  and  re-precipitated 
on  neutralization  of  the  acid  with  ammonia  or  soda,  and 
the  addition  of  a  little  more  of  the  precipitant.  If  the 
second  method  of  cleaning  the  beaker  is  followed,  remem- 


§    39.       FILTRATION.  31 

ber  to  subtract  the  weight  of   I'l,  or  1' 1^  filter-ash  from 
the  weight  of  the  ignited  residue  instead  of  1  as  usual. 

•      FILTRATION. 

39.  a. — Solid  particles  are  separated  from  the  liquids 
Avith  which  they  may  be  mixed  by  the  process  of  filtra- 
tion, referred  to  in  the  preceding  paragraph,  which  con- 
sists simply  in  passing  the  liquid  through  porous  unsized 
paper,  that  intercepts  the  solid. 

.  Paper,  already  cut  in  convenient  sizes,  can  be  had  of 
apparatus  dealers.  For  quantitative  purposes,  filters  of 
Swedish  paper  should  be  used,  or  common  white  filters 
that  have  been  washed  in  dilute  acid ;  to  wash  filters, 
pour  over  them,  in  layers  of  moderate  thickness  in  a  large 
evaporating  dish,  a  mixture  of  one  part  of  hydrochloric 
acid  and  nine  parts  of  water ;  digest  for  several  hours  at 
a  moderate  temperature,  wash  with  distilled  water  by  de- 
cantation  until  the  washings  no  longer  redden  litmus, 
transfer  the  bunches  of  paper  to  blotting  paper,  and  leave 
them  undisturbed  until  the  filters  can  be  separated  from 
each  other  without  being  torn.  These  washed  filters 
are  more  suitable  for  filtration  by  Bunsen's  process  than 
those  of  Swedish  paper,  as  they  are  stronger  and  less  lia- 
ble to  be  torn. 

To  make  the  filter,  fold  the  circular  piece  of  paper  twice 
in  directions  at  right  angles  to  each  other,  and  through 
the  centre  ;  open  the  quadrant  thus  formed  in  such  a  man- 
ner as  to  make  a  conical  cavity,  put  it  in  a  glass  funnel, 
which  should  be  at  least  3-5  millimetres  larger  than  the 
filter,  wet  the  latter  with  a  httle  water  from  the  washing- 
bottle,  and  press  it  closely  agamst  the  glass  throughout 
with  the  finger. 

The  filter  should  never  be  filled  Avith  the  liquid  to 
within  less  than  6  mm.  of  the  top,  and  should  not  ordi- 
narily be  much  more  than  half  filled  with  the  precipitate 
when  the  liquid  has  drained  off. 


32  §    39.       ANALYTICAL    MANIPULATION. 

Most  liquids  may  be  filtered  much  more  rapidly  when 
hot,  and  many  precipitates  are  much  less  liable  to  pass 
through  the  filter,  or  to  choke  it  up,  -when  formed  in  nearly 
boiling  hot  solutions  by  hot  reagents. 

When  possible,  it  is  best  to  let  the  solid  matter  settle 
to  the  bottom  of  the  vessel  containing  the  mixture  of 
liquid  and  precipitate,  then  to  decant  as  much  as  possible 
of  the  clear,  supernatant  liquid  on  the  filter,  pour  fresh 
distilled  Avater  over  the  contents  of  the  beaker,  stir  well, 
and  perhaps  heat  almost  to  boiling,  let  the  precipitate  set- 
tle, and  decant  the  liquid  again  ;  this  may  be  repeated 'a 
number  of  times  before  putting  the  solid  substance  on  the 
filter. 

If  the  precipitate  is  to  be  dissolved  without  weighing 
or  ignition,  it  is  generally  best  to  wash  it  altogether  by 
decantation,  and  then  to  pour  the  solvent  over  the  filter 
through  which  the  decanted  liquid  was  passed,  and  collect 
it  in  the  beaker  containing  the  main  portion  of  the  'w'^shed 
precipitate ;  the  precipitate  may  then  be  digested  with 
the  reagent  if  necessary,  and,  afterwards^  the  filter  well 
washed  out  with  water,  that  is  added  to  the  solution  just 
made  ;  in  this  way  we  may  avoid  any  considerable  dilu- 
tion of  the  solvent  before  it  has  had  time  to  act  on  the 
substance  to  be  dissolved.  If  the  solvent  is  one  that,  in 
its  concentrated  state,  would  attack  the  paper,  it  may  be 
230ured  at  once  over  the  precipitate  in  the  beaker,  while 
another  portion  may  be  diluted  somewhat,  and  passed  re- 
peatedly through  the  filter,  to  take  up  the  small  quantity 
of  the  substance  on  that. 

The  thorough  washing  of  precipitates  and  residues, 
that  is  so  essential  in  quantitative  analysis,  and  is  often 
not  unimportant  in  qualitative  work,  may  sometimes  be 
greatly  facilitated  by  this  process  of  decantation,  particu- 
larly if  the  solid  is  one  that  settles  readily ;  but  if  Bun- 
sen's  process  of  filtration  is  followed,  decantation  may  be 
dispensed  with. 


§  39.     filtration;  bunsen's  process.  33 

In  washing  precipitates  on  the  filter,  the  washing-bottle 
is  an  indispensable  aid.  This  consists  simply  of  a  flask 
of  a  capacity  of  150-1000  c.c,  according  to  the  purpose 
for  which  it  is  to  be  used,  closed  by  a  good  cork  that  is 
pierced  Avith  two  holes ;  through  one  of  these  holes  passes 
a  glass  tube,  8  or  10  cm.  long,  that  extends  just  beyond 
the  coik  on  tlie  inside,  and,  outside,  is  bent  at  an  angle 
of  about  110° ;  the  tube  that  passes  through  the  other 
hole  extends  nearly  to  the  bottom  of  the  flask,  and,  out- 
side, is  bent  at  an  angle  of  about  70°,  and  drawn  out  to  a 
small  jet  at  the  end;  water  in  the  flask  is  forced  out  at 
this  jet  on  blowing  air  in  at  the  mouth  of  the  shorter 
tube. 

Each  portion  of  water  with  which  a  precipitate  on  the 
Clter  is  washed  should  be  allowed  to  pass  through  com- 
pletely before  another  is  added,  and  the  prccii^itate  should 
be  stirred  up  as  much  as  possible  by  the  jet  from  the 
wash-bottle  witli  .each  fresh  addition. 

Insoluble  residues  and  precipitates  must  be  washed, 
particularly  in  quantitative  operations,  as  long  as  the  wash- 
water  carries  oflT  any  notable  quantity  of  matters  in  solu- 
tion ;  the  washings  are  tested  by  evaporating  a  drop  to 
dryness  on  platinum  foil,  to  see  if  any  residue  is  left,  or 
by  a  chemical  test,  as,  for  example,  when  washing  a  pre- 
cipitate of  baric  sulphate  that  was  formed  by  adding 
baric  chloride  to  a  solution  of  a  sulphate;  r.s  long  as  any 
of  the  soluble  chloride  remains  in  the  pores  of  the  filter, 
or  adheres  to  the  precipitate,  and  is  taken  up  by  the 
Vv'ater,  the  washings  Avill  give  the  usual  reaction  for 
clilorine  with  argentic  nitrate  (§  63). 

When  the  contents  of  the  filter  are  to  be  weighed  or 
ignited,  dry  the  whole  together  in  the  drying-chamber  or 
air-bath,  with  the  funnel  well  covered  with  filter  paper. 

K  A  metliod  lately  devised  by  Bunsen  {Annalen  dcr 
Chemie,  148,  270.  American  Jonrnal  of  Science  and 
Art,  2d  Series,  47,  321)  for  iiicreasing  the  rapidity  of  fil- 


84  §    39.       ANALYTICAL    MANIPULATION. 

tration,  and  of  the  washing  of  precipitates,  promises  to  be 
very  useful. 

He  supports  the  filter  by  a  hollow  cone  of  thin  plat- 
inum foil  in  the  throat  of  the  funnel,  and  then  rarefies 
the  air  in  the  funnel-tube;  the  excess  of  pressure  on  the 
liquid  in  the  filter  causes  it  to  flow  througli  very  rapidly, 
while  there  is  no  danger  of  tearing  the  paper. 

To  make  the  platinum  funnel,  a  cast  of  the  glass  funnel 
must  first  be  taken.  Select  a  funnel  with  perfectly  smooth 
and  straight  sides,  ai)d  opening  at  an  angle  of  60°,  fit  in 
it  a  piece  of  oiled  Avriting  paper  in  such  a  manner  that  it 
shall  touch  the  glass  everywhere,  like  an  ordinary  well- 
fitted  filter,  and  fasten  the  paper  in  place  with  two  or 
three  drops  of  sealing-wax  around  the  rim.  Half  fill  the  fun- 
nel then  with  gypsum  paste,  into  which,  before  it  hardens, 
a  plug  of  wood  is  inserted,  to  serve  as  a  handle.  When  the 
gypsum  cone  has  hardened,  remove  it  from  the  funnel,  oil 
the  paper  again,  and  plunge  it,  with  the  paper  still  adher- 
ing, into  a  large  porcelain  crucible  filled  with  another  por- 
tion of  gypsum  paste ;  v>^hen  tliis  mould  has  hardened, 
take  the  cone  out  and  rub  ofi*  the  paper  Avith  the  fingers. 
g  Now,  cut  out  a  piece  of  thin  plat- 

inum foil  Aveighing  about  0.154  grm., 
of  the  precise  shape  and  size  repre- 
sented in  the  adjoining  figure,  with  a 
slit  running  from  h  to  a^  the  centre 
of  the  circle  of  Avhich  the  arc,  c  c  c?, 
forms  a  part ;  ignite  it  in  the  flame  of 
the  lamp  to  make  it  perfectly  flex- 
ible, lay  the  gypsum  cone  on  it  so  that  the  apex 
of  the  cone  shall  coincide  with  a^  bring  up  the  edge,  a  h  c7, 
and  press  it  well  against  the  cone,  and  then  do  the  same 
with  the  edge,  ab  c  ;  after  fitting  the  foil  to  the  cone  as 
l^erfectly  as  possible  Avith  the  fingers,  put  the  Avhole  in  the 
mould  in  the  crucible,  and  revolve  the  cone  back  and 
forth  until  the  platinum  has  taken  the  exact  shape  of  the 


§  39.     filtration;  bunsen's  process.  35 

plaster  casts,  and  retains  its  form  when  removed  from  the 
mould ;  if  found  necessary,  it  may  be  ignited  once  more 
and  shaped  in  the  mould  with  the  cone.  It  may  be  sol- 
dered at  its  upper  edge  by  a  grain  of  gold  and  borax,  so 
that  it  will  be  less  liable  to  get  out  of  shape,  but  this  is 
not  necessary.  If  properly  made,  the  light  should  not  be 
visible  through  tlie  point  of  this  platinum  funnel  when  it 
is  held  before  the  window. 

With  the  platinum  funnel  in  the  throat  of  the  glass 
funnel,  adjust  the  paper  filter,  which  may  be  much  small- 
er than  would  be  used  in  the  ordinary  way  of  filtering,  in 
the  usual  manner,  with  special  care  to  secure  perfect  con- 
tact between  the  filter  and  the  funnel  at  all  points.  Con- 
nect the  tube  of  the  funnel  with  a  large,  strong  glass 
flask,  by  means  of  a  rubber  cork  pierced  with  two  holes, 
BO  that  the  tube  extends  about  G  cm.  beyond  the  cork ; 
through  the  other  hole  pass  a  short  glass  tube  so  that  it 
extends  just  to  the  lower  surface  of  the  cork ;  this  tube 
should  be  bent  once  at  a  right  angle  outside  of  the  flask ; 
it  may  be  connected  with  a  small  brass  stop-cock  by 
means  of  a  short  rubber  tube  with  a  small  bore  and  very 
thick  walls  ;  all  the  rubber  tubing  used  in  the  apparatus 
should  be  of  this  kind. 

Now,  pour  the  liquid  to  be  filtered  on  the  filter,  rarefy 
the  air  in  the  flask,  and  keep  the  former  full  as  long  as 
any  of  the  liquid  remains.  The  precipitate  may  be  al- 
lowed to  come  within  1  mm.  of  the  edge  of  the  filter. 

In  washing  the  precipitate,  pour  the  water  from  a  flask, 
fill  up  to  about  a  centimetre  above  the  rim  of  the  filter, 
with  care  not  to  disturb  the  precipitate,  and  let  each  por- 
tion of  water  drain  off  completely  before  adding  a  fresh 
quantity ;  thus  the  w^ashing  may  be  thoroughly  effected 
in  a  Avonderfully  short  time  ;  if  the  vacuum  in  the  flask 
is  nearly  perfect,  or  the  pressure  on  the  filter  is  nearly  an 
atmosphere,  three  or'  four  washings  suflice,  even  in  the 
case  of  precipitates  that  are  the  most  diflicult  to  wash. 


36  §    39.       ANALYTICAL   MANIPULATION. 

Moreover,  tlie  precipitate  is  so  completely  deprived  of  its 
water,  that  it  may  be  easily  removed  from  the  filter,  or 
can  be  ignited  at  once  without  further  drying. 

To  ignite  the  precipitate  at  once,  Bunsen  directs  to  wrap 
the  filter  around  it,  put  the  whole  in  the  crucible,  set  the 
latter  on  its  side  as  usual,  apply  the  heat  at  the  top  of 
the  crucible  first,  and  gradually  carry  it  towards  the  bot- 
tom as  the  filter  is  burned. 

The  rarefaction  of  the  air  may  be  produced  in  various 
ways.  The  flask  may  be  connected  with  the  upper  end 
of  a  water-pipe  30  feet  high  in  such  a  manner  as  to  make' 
a  Sprengel's  air-pump.  Desaga,  of  Heidelberg,  furnish- 
es a  complete  apparatus  for  this  purpose. 

Or,  an  air-tight  connection  may  be  made  between  two 
large  glass  bottles,  or  demijohns,  by  means  of  a  long  piece 
of  thick  walled  rubber  tubing  ;  then  put  one  bottle  filled 
,  with  water  on  a  high  shelf,  while  the  other  is  put  on  the 
floor,  connect  the  filtering-flask  witli  a  tube  leading  just 
through  the  cork  of  the  upper  bottle,  allow  the  water  to 
flow  from  the  upper  bottle  to  the  lower  one,  while  pro- 
vision is  made  for  the  escape  of  the  air  from  this  lower 
bottle ;  the  rarefaction  of  the  air  in  the  filtering-flask  will 
follow.  When  all  the  water  has  flowed  from  the  upper 
to  the  lower  bottle,  their  relative  positions  may  be  re- 
versed, the  proper  connection  made  between  the  flltering- 
flask  and  the  upper  bottle,  and  the  filtration  continued. 

Or,  a  small  demijohn  may  be  closed  by  a  rubber  cork 
through  which  passes  a  glass  tube,  connected  with  a 
small  brass  stop-cock;  connect  the  demijohn  with  an  air- 
pump,  exhaust  the  air,  close  the  stop-cock,  connect  the 
demijohn  with  the  filtering-flask,  and  open  the  stop-cock 
when  all  is  ready  for  the  filtration.  In  order  to  prevent 
acid  fumes  or  ammonia  coming  from  the  filtered  liquid 
from  injuring  the  stop-cock,  a  wash-bottle,  containing 
sodic  hydrate  or  sulphuric  acid,  may  be  interposed.  (J 
M.  Crafts.) 


§    39.       FILTRATION.  37 

For  fuller  details  in  regard  to  this  mode  of  filtration 
we  refer  to  the  original  articles. 

c.  When  several  portions  of  a  solvent,  such  as  water, 
alcohol,  or  ether,  are  to  be  made  to  act  on  a  substance, 
each  portion  can  be  readily  separated  from  the  substance 
by  the  following  contrivance. 

Close  the  flask  with  a  rubber  cork  pierced  with  two 
holes ;  through  one  of  these  pass  a  short  bent  tube,  like 
the  shorter  tube  of  the  common  washing-bottle,  and  in 
the  other  hole  fit  a  tube  which  is  widened  out,  funnel-like, 
at  one  end,  but  not  so  much  as  to  prevent  its  being  put 
into  the  flask  easily  ;  near  the  other  end,  this  tube  is  bent 
at  an  acute  angle,  and  the  end  is  drawn  out  to  a  point 
and  left  with  a  pretty  large  opening,  after  the  fashion  of 
the  other  tube  of  the  washing-bottle ;  the  long  arm  of 
the  tube  should  reach  nearly  to  the  bottom  of  the  flask, 
and  have  a  piece  of  fine  linen  firmly  bound  over  its  mouth. 

The  substance  and  the  solvent  having  been  digested  in 
the  flask,  when  the  solvent  is  supposed  to  be  saturated, 
and  it  is  desired  to  replace  it  by  a  fresh  quantity,  force 
air  into  the  flask  by  the  shorter  tube  and  the  solution  will 
be  expelled,  and  at  least  partially  filtered  on  its  way 
through  the  muslin ;  then,  if  the  end  of  the  longer  tube 
is  inmiersed  in  a  fresh  quantity  of  the  solvent,  this  may 
be  drawn  into  the  flask  by  suction  at  the  mouth  of  the 
short  tube. 

If  heat  is  used,  the  mouth  of  the  short  tube  may  be 
connected  with  the  Ic^wer  end  of  a  Liebig's  condenser ; 
then  tlie  vapors  of  the  solvent  are  condensed,  and  the 
liquid  flows  back  into  the  flask,  and  the  ebullition  can  be 
maintained  as  long  as  is  desired  without  the  necessity  of 
adding  fresh  quantities  of  the  solvent  to  replace  what  is 
lost  by  evaporation ;  when  it  does  become  necessary  to 
replace  this  portion  of  the  solvent  by  a  fresh  one,  the  rub- 
ber tube  that  connects  the  flask  with  the  condenser  may 
be  closed  with  a  clamp,  and,  the  application  of  heat  being 


38  §    40.       ANALYTICAL   MANIPULATION-. 

continued,  the  liquid  will  be  forced  out  through  the  mus- 
lin filter ;  on  immersing  the  open  end  of  the  longer  tube 
in  a  fresh  quantity  of  the  solvent,  and  removing  the  lamp, 
this  liquid  will  flow  in. 

The  solution  may  not  bo  perfectly  clarified  in  passing 
through  the  linen  filter,  in  which  case  it  will  have  to  be 
filtered  again  through  paper. 

To  efiect  more  perfect  filtration,  a  thick  mat  of  gun- 
cotton  may  be  bound  over  the  linen ;  this  layer  of  cotton 
should  not  be  anywhere  less  than  14  mm.  thick. 

WEIGHING  OF  RESIDUES  AND  PRECIPITATES. 

40.  When  it  is  possible,  residues  or  precipitates  are  ig- 
nited before  being  weighed. 

This  ignition  may  be  performed  in  two  ways. 

a.  If  the  substance  is  not  altered  in  its  chemical  com- 
position by  contact  with  burning  organic  matter,  or  at 
the  somewhat  high  temperature  that  is  sometimes  neces- 
sary to  efiect  the  complete  incineration  of  the  filter,  roll 
the  well-dried  filter  together  around  the  precipitate,  put 
the  whole  in  the  previously  ignited  and  weighed  crucible, 
cover  and  heat,  at  first  very  gently  ;  when  the  filter  is 
completely  charred  and  no  more  smoke  is  given  off*,  turn 
the  crucible  on  its  side,  lay  the  cover  partly  on  the  edge 
of  the  crucible  and  partly  on  the  triangle,  and  heat  the 
contents  of  the  crucible  until  the  ash  is  quite  Avhite. 

J).  If  the  filter  may  not  be  burned  in  direct  contact 
with  the  preciiiitate,  crush  and  work  it  gently  between 
the  fingers  over  a  sheet  of  glazed  paper,  to  loosen  the  pre- 
cipitate as  much  as  possible,  place  the  crucible  on  the 
glazed  paper,  and  empty  the  contents  of  the  filter  into  it. 
Put  the  crucible  on  the  porcelain  plate  belonging  to  the 
Bunsen's  burner,  open  the  filter  on  another  piece  of 
glazed  paper,  fold  its  edges  up  so  as  to  make  a  little  tray, 
with  a   soft  feather  carefully  brush  into  this   tray  any 


§    40.       WEIGHING    OF    RESIDUES    AXD    PRECIPITATES.    39 

particles  of  the  precipitate  that  may  have  fallen  on  tlie 
first  piece  of  paper,  roll  the  filter  up,  enclose  it  in  a  short 
spiral  on  one  end  of  a  platinum  wire  that  was  weighed 
with  the  crucible,  hold  it  over  the  crucible,  and  set  fire  to 
it ;  by  applying  tlie  charred  filter  to  the  flame  of  the 
lamp  two  or  three  times  it  may  be  almost  completely  in- 
cinerated ;  finally,  either  let  the  ash  and  the  wire  drop 
into  the  crucible  and  ignite  the  whole  four  or  five  minutes, 
or  until  the  ash  is  white,  or,  in  case  the  filter-ash  must  be 
kept  entirely  separate  from  the  precipitate,  let  the  two 
drop  into  the  hollow  lid  of  the  crucible,  and  ignite  the 
precipitate  and  ash  separately. 

The  glazed  paper  used  above  should  be  of  a  light  color 
if  the  j)recipitate  is  dark-colored,  and  vice  versa,  and  the 
whole  operation  should  be  performed  in  a  place  free  from 
currents  of  air. 

c.  If  the  quantity  of  the  pi-ecipitate  is  very  small,  and 
yet  is  of  such  a  nature  as  to  be  partly  reduced  to  a  lower 
degree  of  oxidation  if  ignited  with  the  filter,  the  ignition 
may  be  performed  as  in  a  ;  when  it  is  completed,  put  a 
piece  of  diy  amnionic  nitrate  in  the  crucible,  cover  well, 
and  ignite  again,  but  very  gently  at  first. 

Ferric  oxide  or  baric  sulpliate  may  be  ignited  in  this 
way  when  nothing  better  can  be  done. 

Sometimes,  when  a  portion  of  the  filter  is  very  difficult 
to  incinerate  completely,  the  combustion  may  be  facilita- 
ted by  adding  a  little  animonic  nitrate  as  above. 

After  weighing,  subtract  the  weight  of  the  filter-ash, 
which  has  been  determined  once  for  all  for  the  particular 
kind  and  lot  of  paper  and  size  of  filter  used,  by  the  incin- 
eration of  half  a  dozen  or  a  dozen  together,  and  dividnig 
the  total  weight  of  the  ash  thus  obtained  by  the  number 
of  filters  burned. 

d.  If  the  substance  to  be  weighed  cannot  be  ignited,  a 
filter  should  be  previously  thoroughly  dried  in  the  steam 
or  air-bath  at  the  same  temperature  to  which  it  is  after- 


40  §    41.       ANALYTICAL    MANIPULATION. 

wards  to  be  exposed  with  the  precipitate,  and  weighed, 
either  between  two  watch-glasses  with  ground  edges  and 
fitting  well  together,  or  in  a  stoppered  glass  tube ;  after 
careful  drying  with  the  precipitate,  it  is  again  weighed  in 
the  same  manner.  It  should  then  bo  dried  an  hour 
longer  and  weighed  again,  and  this  should  be  repeated 
until  a  constant  weight  is  obtained.  Swedish  filter-paper 
or  Avashed  filters  should  always  be  used  in  this  operation. 

c.  The  substance  that  has  been  dried  or  ignited,  and  is 
to  be  weighed,  should  always  be  allowed  to  cool  under  a 
bell-glass  over  concentrated  sulphuric  acid,  or  in  the  des-' 
iccator  more  commonly  used  for  this  purpose  ;  this  desic- 
cator consists  simply  of  a  short  and  wide  glass  cylinder, 
with  a  ground  edge  upon  which  a  ground  glass  plate  will 
fit  closely,  particularly  if  the  edge  is  smeared  with  a  lit.l3 
tallow. 

The  pair  of  watch-glasses  containing  the  dried  filter, 
or  the  crucible  with  the  ignited  precipitate,  rests  on  a  tri- 
angle in  the  cylinder  over  fused  calcic  chloride,  with 
which  the  bottom  is  covered. 

No  object^ should  be  weighed  until  it  is  entirely  cold. 

/.  Platinum  vessels,  after  having  been  heated  by  gas, 
should  be  rubbed  with  a  little  sand  on  the  moistened  fin- 
ger. The  sand  should  be  fine,  and  all  its  grains  should 
be  rounded.  The  crucible  should  also  be  cleaned  from 
time  to  time  by  fusing  a  little  potassic  bisulphate  in  it. 
The  crucible  should  be  supported  over  the  lamp  on  stout 
platinum  wire,  which  is  stretched  from  side  to  side  of  a 
larger  iron-wire  triangle,  in  such  a  manner  as  to  make  a 
second  triangle  inside  of,  and  about  C  mm.  smaller  than, 
the  iron  triangle. 

MEASURING  AND  DIVIDING  SOLUTIONS. 

41.  For  these  purposes  graduated  pipettes  and  cylin- 
ders, and  'I,,  '  !„,  and  1  litre  flasks  are  used. 


§    41.       MEASURING   AND    DIVIDING   SOLUTIONS.  41 

The  analyst  slioukl  test  tlie  correctness  of  the  gradua- 
tion of  his  instruments  before  using  them,  by  comparing 
them  with  each  other;  the  '1^  litre  flask  should  require 
just  as  much  water  to  fill  it  twice  up  to  the  mark  on  the 
neck  as  is  required  to  fill  the  '  \^  litre  flask  once  up  to  the 
mark  on  its  neck.  In  the  same  way  the  '  |,  litre  flask 
should  be  compared  with  the  1  litre  flask,  and  these  with 
the  graduated  cylinders,  and  the  pipettes  with  each  other 
and  the  graduated  cylinders. 

When  a  certain  quantity  of  any  standard  or  titrated 
solution  is  to  be  measured  out  with  a  pipette  or  flask,  the 
instrument  should  either  be  dry  on  the  inside,  or  it  should 
be  rinsed  out  with  a  little  of  the  solution  to  be  measured, 
and  the  last  drop  of  the  solution  that  remains  in  the  point 
of  the  pipette  should  either  always  be  allowed  to  remain 
there,  or  it  should  always  be  blown  out  into  the  vessel 
containing  the  measured  solution ;  the  same  course  should 
be  followed  in  testing  the  graduation  of  the  pipettes. 

To  read  ofl"  the  lieight  of  a  solution  in  a  burette  or 
other  graduated  instrument,  be  sure,  first,  that  it  is  in  a 
vertical  position,  so  that  the  surface  of  the  liquid  in  it 
will  be  horizontal ;  then  place  the  cylinder  between  the 
eye  and  a  brightly  illuminated  white  wall,  and  read  the 
height  of  the  lower  surface  of  the  dark  zone  that  is  read- 
ily seen  under  these  circumstances  just  beneath  the  sur- 
face, while  the  eye  is  in  the  same  horizontal  plane. 

In  filling  a  Mohr's  burette,  fill  up  to  above  the  zero 
mark  with  the  solution,  and  quickly  oj)en  wide  the  clamp 
for  a  moment  so  that  the  rubber  tube  and  the  glass  tube 
below  the  clamp  will  be  completely  filled ;  then  open  the 
clamp  a  little  and  allow  the  liquid  to  flow  out,  drop  by 
drop,  until  the  dark  zone,  mentioned  above,  reaches  the 
zero  mark. 

The  temperature  of  all  measured  liquids  should  be  as 
nearly  15°  C.  as  possible. 

When  the  quantity  of  a  solution  to  be  divided  is  not 


42  §    4,2.       ANALYTICAL   MAI^-IPULATIOX. 

too  large,  the  division  may  be  more  accurately  made  by 
weighing  than  by  measuring.  Get  the  weight  first  of  the 
whole  amount  of  tlie  liquid,  in  a  small  flask,  pour  out 
about  the  quantity  desired  for  a  particular  analysis,  and 
weigh  the  flask  again  with  the  remainder  of  the  liquid  ; 
pour  out  another  quantity  and  weigh  again,  and  so  on 
until  the  division  is  completed. 

For  this  purpose,  a  fl:\sk  with  a  little  spout,  attached 
just  below  Avhere  the  neck  widens  out  into  the  body,  will 
be  found  very  convenient. 

CxVLCULATION  OF  RESULTS. 

42t  The  results  of  an  analysis  are  usually  calculated  so 
as  to  give  the  per  cent  composition  of  the  compound 
analyzed. 

If  the  substance  determined  is  weighed  or  estimated  in 
the  form  in  which  it  existed  in  the  compound,  and  it  was 
determined  in  the  undivided  solution  of  the  same,  noth- 
ing remains  to  be  done  but  to  estimate  the  percentage  by 
a  simple  rule-of-three  calculation,  in  which  the  amount 
taken  for  analysis  is  the  first  term,  the  amount  of  the  sub- 
stance found  the  second,  and  100  the  third. 

If  the  substance  was  determined  in  a  fractional  part  of 
the  solution,  the  same  fractional  part  of  the  weight  of  the 
compound  taken  for  analysis  must  be  made  the  first  term 
of  the  proportion ;  or  the  amount  of  the  substance  found 
may  be  estimated  for  the  whole  amount  of  the  original 
solution  by  multiplication  by  the  proper  number,  and  this 
product  is  then  made  the  second  term  of  the  proportion, 
the  first  term  being  the  weight  of  the  whole  amount  taken 
for  analysis. 

In  gravimetrical  analysis  the  substance  is  usually 
weighed  in  the  form  of  some  insoluble  compound  that 
did  not  exist  at  all  in  the  compound  analyzed,  and  the 
amount  of  the  substance  in  the  weight  that  was  found  of 
this  insoluble  compound  must  first  ba  calculated. 


§  42.     calOulatiox  of  kesults.  43 

This  may  be  effected  by  a  rule-of-three  calculation  also, 
in  whicii  the  molecular  weight  cf  the  insoluble  sub- 
stance is  made  the  first  term,  the  weight  of  the  substance 
sought  in  a  molecule  of  the  insoluble  substance  the  second, 
and  the  weight  of  the  insoluble  compound  found  the  third. 

For  example,  in  a  determination  of  sulphuric  acid,  SO3, 
1.13  grm.  of  baric  sulphate  was  found;  then  we  have 

BaSO,     :     SO3  =  BaSO,     :     SO3 

233  :     80     =  1.13         :    0.3879  grm. 

The  same  result  can  be  more  expeditiously  obtained, 
however,  with  the  aid  of  Table  III,  where  for  each  special 
case  a  part  of  this  calculation  has  already  been  perform- 
ed, namely,  the  division  of  the  second  term  by  the  first ; 
nothing  is  left  to  be  done,  therefore,  but  to  multiply  the 
weight  of  the  insoluble  compound  found,  whose  name  U 
given  in  the  first  column,  by  the  decimal  in  the  second 
column  against  the  name  of  the  substance  sought  in  the 
third  column.  In  the  above-mentioned  case  we  find,  on 
consulting  the  table,  the  proper  decimal  against  tlie 
names  sulphuric  acid  and  baric  sulphate  is  0.3433,  which 
multiplied  into  1.13  grm.  =  0.3879. 


44  8    43.       BASES    AND    ACIDS    WITH    IlEAGENTS. 


CHAPTER    III. 

BEHAVIOR  OF  THE  MORE  COMMON  BASES  AND  ACIDS  WITH 
REAGENTS,  AND  THEIR  QUANTITATIVE  ESTIMATION. 

43.  The  substances  for  whose  qualitative  detection  or 
quantitative  estimation  directions  are  given  in  the  follow- 
ing pages,  are  as  follows. 

1.  Inorganic^  basic  elements. — Potassium,  sodium,  bari- 
um, calcium,  magnesium,  aluminium,  iron,  manganese,  zinc, 
lead,  and  copper. 

2.  Volatile,  basic  radical. — Ammonium. 

3.  Acid  elements  and  inorganic  acids. — Arsenic,  chlo- 
rine, iodine,  fluorine,  sulphur,  and  sulphuric,  phosphoric, 
carbonic,  silicic,  and  nitric  acids. 

4.  Compound,  acid  radicals. — Cyanogen  and  ferrocy- 
anogen. 

5.  Organic  acids. — Oxalic,  acetic,  tartaric,  citric,  malic, 
uric,  hippuric,  lactic,  and  tannic  acids. 

6.  Indifferent  organic  substances. — Cellulose,  starch, 
sugar,  gum,  albuminoids,  urea,  fat,  and  alcohol. 

POTASSIUM.     K.    C9.1 

44( — Salts  of  potassium,  with  all  the  acids  mentioned 
in  §  43,  except  tartaric,  are  easily  soluble  in  water.  The 
tartrate  is  soluble  in  free  alkali  or  mineral  acid,  or  in 
considerable  water. 

Reactions* — In  tolerably  concentrated,  neutral  or 
slightly  acid  solutions  of  potassic  salts,  containing  hydro-* 
chloric  acid  or  a  soluble  chloride,  platinic  chloride,  PtCI^, 
gives  a  yellow,  granular,  crystalline  precipitate,  K,,PtClp, 
which  is  sparingly  soluble  in  water,  and  nearly  insoluble 
in  alcohol.      Its    solubility  is  slightly  increased   by  the 


§   44.      POTASSIUM.  45 

presence  of  free  hydrochloric  acid.  No  precipitate  will 
be  given  by  the  reagent  in  a  very  dilute  sohition  of  the 
potassic  salt,  but  if  such  a  solution  is  evaporated  nearly 
to  dryness  with  a  little  platinic  chloride,  and  alcohol  is 
added  to  the  residue,  the  yellow  double  salt  remains  un- 
dissolved. 

If  a  drop  of  a  solution  of  a  potassic  salt  is  evaporated 
to  dryness  in  the  platinum-wire  loop,  and  the  loop  with 
the  residue  on  it  is  held  at  the  end  of  the  inner  blowpipe 
flame,  or  in  the  corresponding  part  of  the  flame  of  the 
Bunsen  gas-burner,  a  violet  color  is  communicated  to  the 
flame  beyond  the  wire.  Viewed  through  thick  blue  glass, 
this  color  has  a  more  reddish  appearance,  but  the  light  is 
not  entirely  absorbed ;  the  j^resence  of  sodium,  barium, 
calcium,  and  copper,  may  interfere  with  this  reaction. 

In  a  silicate,  this  reaction  for  potassium  may  be  ob- 
tained by  fusing  it,  in  a  fine  powder,  with  pure  gypsum, 
treating  the  fused  mass  with  w^ater,  filtering,  and  testing 
the  filtrate. 

Quantitatiye  estimation* — Potassium  may  be  deter- 
mined as  potassic  chloride,  KCl,  potassic  sulphate,  K^SO^, 
or  potassic  platinic  chloride,  K^PtClg. 

The  first  two  salts  are  soluble  in  water,  and  therefore 
cannot  be  obtained  by  precipitation  ;  other  metals  and 
acids  being  removed  from  the  solution  by  methods  here- 
inafter described,  the  pure  salt  is  then  left  as  a  residue  on 
evaporation  to  dryness. 

a.  Determination  as  potaSSic  chlorldC. — The  solution 
being  freed  from  other  metals  and  acids,  evaporate  it  to 
dryness  over  the  water-bath,  and  ignite  the  residue  in  a 
well  covered  platinum  crucible,  very  gently  for  a  consid- 
erable time  at  first,  to  avoid  the  decrepitation  and  conse- 
quent loss  that  might  result  from  too  rapid  heating; 
finally,  heat  the  crucible  to  a  dull  red  for  a  short  time. 
The  residue  contains  52.41°  |,  of  potassium. 


46  §    44.       BASES    AND    ACIDS    WITH    REAGEJ^TS.       . 

h.  Determination  as  potassic  Sulphate. — The  solution 
being  freed  from  other  metals  and  from  non-volatile  acids, 
as  directed  in  each  special  case,  evaporate  it  to  dryness 
and  ignite  the  residue  in  a  platinum  crucible,  as  directed 
for  the  ignition  of  potassic  chloride,  except  tliat  it  may 
be  more  strongly  heated  at  the  close  of  the  operation. 

If  volatile  acids,  such  as  hydrochloric,  nitric,  or  acetic, 
are  present  in  tlie  solution  containing  the  potassium  to  be 
determined,  sufficient  sulphuric  acid  must  be  added  before 
evaporation  to  expel  them;  in  order,  however,  to  avoid 
the  disagreeable  operation  of  expelling  a  large  excess  of 
sulpliuric  acid  also,  it  is  well  to  add  but  little  at  first ;  the 
evidence  that  enough  has  been  used  will  be  found  in  the 
evolution  of  abundant  white  acid  fumes  towards  the  close 
of  the  evaporation ;  if  these  fumes  do  not  appear,  of 
course  a  little  more  acid  must  be  added,  and  the  evapora- 
tion continued. 

After  igniting  the  residue  in  the  j)latinum  crucible 
gently  for  a  little  while,  put  in  a  small  fragment  of  well 
dried  amnionic  carbonate,  and  ignite  again  while  the 
crucible  is  loosely  covered,  very  gently  at  first,  and  then 
gradually  raise  the  heat  to  a  full  red ;  repeat  this  addition 
of  ammonic  carbonate  and  the  subsequent  ignition  as 
lonsr  as  there  is  any  chanixe  in  weii^ht. 

The  ignition  with  ammonic  carbonate  facilitates  the  ex- 
pulsion of  the  second  equivalent  of  sulphuric  acid  from 
the  potassic  bisulphate,  and  it  should  be  used  in  the  man- 
ner indicated  whenever  free  sulphuric  acid  was  present  in 
the  solution  that  was  evaporated.  The  residue  of  potassic 
sulphate  contains  44.89'' |„  of  potassium,  or  54.08°  |^  of 
potassa. 

c.  The  determination  of  potassium  as  potassic  platinic 
chloride  depends  upon  the  insolubility  of  this  conqjound 
in  alcohol. 

The  solution  being  freed  from  all  except  potq,ssic  and 
sodic  chlorides,  and,  according  to  Stohraann,  calcic  and 


§   44.       POTASSIUM.  47 

magnesic  chlorides  also,  and  highly  concentrated,  add 
platinic  chloride  in  excess,  until  the  liquid  has  a  bright 
yellow  color,  and  evaporate  the  mixture  nearly  to  dryness 
over  the  water-bath,  with  care  not  to  heat  the  water  quite 
to  boiling. 

Pour  alcohol  of  84"  1^,,  mixed  with  '|g  its  volume  of 
ether,  over  the  residue,  let  stand  several  hours  in  a  well 
covered  vessel,  with  occasional  stirring,  transfer  the  in- 
soluble double  chloride  to  a  dried  and  weighed  filter, 
wash  it  with  alcohol  and  ether  mixed  as  above  directed, 
dry  at  100°  C,  and  weigh. 

If  great  accuracy  is  required,  evaporate  the  filtrate 
from  this  first  portion  of  the  chloride  nearly  to  dryness, 
at  a  temperature  not  above  75°  C,  after  addition  of  some 
water  and  more  i^latinic  chloride,  and  some  sodic  chlo- 
ride if  but  little  of  this  is  supposed  to  be  present,  and 
treat  this  almost  dry  residue  with  the  mixture  of  alcohol 
and  ether  as  above ;  if  a  second  quantity  of  insoluble 
chloride  is  thus  obtained,  collect  it  on  a  filter,  wash,  dry, 
and  weigh  it,  and  add  the  amount  so  found  to  the  first 
quantity. 

The  salt  contains  16"|  „  of  potassium. 

If  the  quantity  of  the  precipitate  is  quite  small,  less 
than  0.03  grm.  or  thereabouts,  it  is  better  to  collect  it  on 
a  small  filter,  incinerate  the  filter,  add  a  little  pure  oxalic 
acid  to  the  cooled  residue,  cover  the  crucible,  and  ignite 
again  gently  at  first,  and  more  strongly  afterwards  ;  after 
this  ignition  nothing  but  platinum  and  potassic  chloride 
remains ;  dissolve  out  the  salt  by  washing  the  residue 
with  water  until  the  washings  give  no  turbidity  with  ar- 
gentic nitrate,  and  dry,  ignite,  and  weigh  the  platinum. 

d.  In  some  cases,  as  in  the  analysis  of  wood-ashes, 
potassium  or  potassa  may  be  determined  by  a  volumetric 
process,  which  consists  in  ascertaining'  the  amount  of  a 
solution  of  sulphuric  acid  of  known  sti-ength,  that  is  re- 


48  §   45.       BASES    AND    ACIDS    WITH    llEAGENTS. 

quired  to  combine  with  it  and  form  a  salt  which  is  neutral 
to  test-papers  (§  45). 

PREPARATION    OF    THE    STANDARD   ACID   AND   ALKALINE 
SOLUTIONS. 

45.  a. — Sulphuric  acid. — To  about  1100  c.c.  of  water 
add  nearly  68  grms.  of  concentrated  sulphuric  acid,  mix 
the  whole  well  together,  let  the  mixture  cuol  to  the  tem- 
perature of  the  working  room,  and  then  estimate  sulphu- 
ric acid  with  baric  chloride  (§  59)  in  two  or  three  portions 
of  20  c.c.  each,  with  the  utmost  care ;  having  in  this  w^ay 
determined  the  strength  of  the  solution,  dilute  it  sq.  tliat 
one  litre  shall  contain  exactly  one  equivalent  of  the  acid 
expressed  in  grammes,  or  40  grms.  Supposing  that  the 
mean  of  three  satisfactory  determinations,  as  above,  gives 
0.84  grm.  of  sulphuric  acid  in  20  c.c. :  then  we  learn  from 
the  proportions,  20  :  0.84  =  1000  :  42,  and  40  :  42  = 
1000  :  1050,  that  50  c.c.  of  water  must  be  added  to  one 
litre  of  the  acid  that  we  have  made,  in  order  that  it  shall 
be  of  tlie  proper  strength ;  to  effect  this  farther  dilution, 
measure  out  1000  c.c.  of  tlie  acid  in  the  litre  flask,  pour 
it  without  any  loss  into  the  bottle  in  which  it  is  to  be 
kept,  rinse  the  walls  of  the  flask  with  exactly  50  c.c.  of 
distilled  Avater,  pour  this  water  likewise  into  the  same 
bottle  without  loss,  and  mix  the  acid  and  rinsings  together 
well;  finally  pour  about  halt*  the  contents  of  the  bottle 
into  the  flask,  rinse  off  the  walls  of  the  flask  with  the 
liquid,  and  pour  it  back  into  the  bottle. 

The  bottle  containing  this  standard  acid  should  be  kept 
well  stoppered  ;  each  time  that  a  portion  is  to  be  taken 
out,  the  contents  of  the  bottle  should  be  shaken  up  in 
such  a  manner  as  to  rinse  down  the  water  that  may  have 
evaporated  in  the  space  above  the  liquid  and  condensed  on 
the  glass.    {Freseniiis.    Quantitative  Chemlsche  Analyse.) 

Since  40  is  the  equivalent  of  sulphuric  anhydride,  SO3, 


§    45.       PREPARATION    OF    THE    STANDARD    SOLUTIONS.    49 

and  this  standard  or  normal  solution  contains  an  equiva- 
lent of  the  anhydride  expressed  in  grammes,  in  a  litre, 
(  =  1000  cubic  centimetres)  it  contains,  then,  an  equivalent, 
expressed  in  milligrammes,  in  one  cubic  centimetre  =  40 
mgr.  or  0.04  grm.  The  quantity  of  acid  in  one  cubic  centi- 
metre will  combine  with  exactly  one  equivalent  of  potassic 
oxide  or  potassa,  K^O,  expressed  in  milligrammes,  =  47.1 
mgr.  or  0.0471  grm.,  and  form  a  salt  whose  solution  is 
neutral  to  test-papers ;  in  a  like  manner,  the  acid  in  one 
cubic  centimetre  of  the  standard  solution  will  combine 
with  or  neutralize  one  equivalent  of  sodic  oxide  or  soda, 
Na^O,  expressed  in  milligrammes  =  31  mgr.  or  0.031  grm., 
or  with  one  equivalent  of  ammonic  oxide,  (ISTHJ^O,  =  26 
mgr.  or  0.026  grm. 

The  neutrality  of  the  solution  may  be  determined  by 
its  effect  on  paper  that  has  been  colored  by  litmus,  or  by 
adding  a  small  quantity  of  a  solution  of  litmus,  or  of 
cochineal  or  curcuma  root.  Litmus  is  colored  blue  by 
free  alkali,  and  red  by  free  acid ;  cochineal  under  the  same 
circumstances  is  colored  purple  and  light  reddish-yellow, 
while  curcuma  or  turmeric  is  colored  brown  by  free  alkali, 
and  yellow  by  acids. 

If,  then,  to  a  solution  containing  any  one  of  the  alkalies 
just  mentioned,  either  in  a  free  state  or  combined  with 
the  weak  carbonic  acid,  we  add  a  little  cochineal  solution, 
and  then  the  standard  acid  from  a  burette  or  a  graduated 
pipette,  with  constant  stirring,  until  the  purple  color  sud- 
denly disappears,  and  a  reddish-yellow  one  takes  its  place, 
that  remains  permanent  throughout  the  whole  liquid,  we 
may  know  that,  for  each  cubic  centimetre  of  acid  added, 
there  were  0.0471  grm.  of  K,0,  or  0.031  of  Na^O,  or  0.026 
of  (NHJP  in  the  solution;  the  whole  amount  of  the  al- 
kali in  the  quantity  of  its  solution  taken  for  analysis  will 
be  given  by  the  product  of  the  number  of  cubic  centime- 
tres of  acid  required,  into  the  corresponding  equivalent 
3 


50  §    45.       BASES    AISTD   ACIDS    WITH    REAGE:NTS. 

of  the  alkali,  expressed  in  milligrammes  or  fractions  of  a 
gramme  as  above. 

h.  Standard  oxalic  acid. — Put  G3  grms.  of  pure  crys- 
tallized oxalic  acid  in  a  litre  flask,  fill  the  flask  up  to 
about  two-thirds  with  water,  and,  after  the  acid  is  entirely 
dissolved,  add  more  water  until  it  rises  nearly  to  the  mark 
on  the  neck  of  the  flask ;  bring  the  water  to  a  tempera- 
ture of  15°  C,  and  then,  holding  the  flask  by  the  rim,  so 
that  it  will  take  a  vertical  position,  carefully  add  water 
up  to  the  mark  on  the  neck.  Mix  the  whole  well  together 
by  shaking,  transfer  the  liquid  to  a  well  stoppered  bottl'e, 
and  keep  it  in  a  dark  place.  As  63  is  the  equivalent  of 
crystallized  oxalic  acid,  expressed  in  grammes,  this  nor- 
mal solution  contains,  like  the  standard  sulphuric  acid, 
one  equivalent  of  the  acid  expressed  in  milligrammes, 
=63  mgr.  or  0.063  grm.,  in  one  cubic  centimetre. 

c.  A  standard  soda  solution  is  often  wanted  in  connec- 
tion with  the  use  of  the  standard  acid,  and  for  other  pur- 
poses, and  its  preparation  may  be  described  here. 

It  is  made  of  such  a  strength  that  one  cubic  centimetre 
of  it  will  be  exactly  neutralized  by  one  cubic  centimetre 
of  the  standard  acid,  or  will  contain  0.031  grm.  of  sodic 
oxide,  Na^O. 

To  prepare  it,  put  5  c.c.  of  the  standard  acid  in  a  small 
flask  with  a  very  little  cochineal  solution,  and  then  add  a 
diluted  solution  of  sodic  hydrate,  of  which  a  considerable 
quantity  has  been  previously  made,  from  a  5  c.c.  pipette 
graduated  into  twentieths  of  a  cubic  centimetre,  very 
slowly  and  with  constant  shaking  of  the  flask,  until  the 
reddish-yellow  color  is  just  changed  to  purple ;  suppose 
that  2  c.c.  have  to  be  added ;  then  evidently  3  c.c.  of  wa- 
ter must  be  added  to  2  c.c.  of  the  soda  solution,  in  order 
to  make  5  c.c.  of  the  latter  that  shall  exactly  neutralize 
5  c.c.  of  the  standard  acid ;  or  ^^^"""  =  the  amount  of 
water  to  be  added  to  one  litre  of  the  sodic  solution,  to 


§  46.     SODIUM.  51 

make  it  of  the  normal  strength.  When  the  solution  has 
been  prepared  according  to  these  directions,  and  the  water 
and  alkali  are  well  mixed,  it  should  be  tested,  to  be  sure 
that  the  equality  between  the  acid  and  the  alkaline  solution 
is  perfect.  Keep  the  solution  in  a  bottle  closed  with  a 
cork,  through  which  j^asses  a  calcic-chloride  tube  that  is 
stopped  at  its  lower  end  with  a  plug  of  cotton  and  then 
filled  with  soda-lime ;  by  this  arrangement;  the  free  ex- 
pansion of  the  air  in  the  upper  part  of  the  bottle  with 
changes  of  temperature  is  permitted,  while  no  carbonic 
acid  can  enter ;  ifc  is  well  to  bend  the  slender  part  of  the 
calcic-chloride  tube  at  a  right  angle  just  above  the  cork, 
so  that  no  soda-lime  can  possibly  fall  into  the  bottle,  and 
to  fill  the  burette  by  means  of  a  small  siphon  passing 
through  the  cork  to  the  bottom  of  the  bottle,  the  longer 
arm  of  which  may  be  closed  at  the  end  by  a  clamp  on  a 
rubber  tube. 

To  100  c.c.  of  this  solution  add  900  c.c.  of  water,  mak- 
ing both  measurements  with  the  utmost  care,  mix  well, 
and  test  this  solution  with  the  standard  acid ;  1  c.c.  of 
the  latter  should  require  exactly  10  c.c.  of  the  former  to 
neutralize  it ;  keep  this  solution  in  the  same  manner  as  de- 
scribed for  the  other  standard  soda  solution,  and  labeled, 
^  Ijo  standard  soda  solution. 

SODIUM.    Na.    23. 

46.  Salts  of  sodium,  with  all  the  acids  named  in  §  43, 
are  soluble  in  water.  The  double  chloride  of  sodium  and 
platinum  is  also  soluble  in  both  water  and  alcohol. 

When  this  solution  is  very  slowly  evaporated  to  dry- 
ness, slender,  rosy,  prismatic  crystals  are  formed,  while 
the  crystals  of  the  corresponding  potassium  salt  are  octa- 
hedral and  granular. 

Reactions. — ^When  a  drop  of  a  solution  of  a  salt  of  so- 
dium is  evaporated  to  dryness  in  the  platinum-wire  loop, 


52  §    46.       BASES    A^^D    ACIDS    AVITH    REAGENTS. 

and  the  loop  is  then  held  at  the  end  of  the  inner  blow- 
pipe flame,  or  in  the  corresponding  part  of  the  flame  of  a 
Bunsen's  gas-burner,  a  yellow  color  is  commuuicated  to 
the  flame  beyond  the  wire. 

These  yellow  rays  are  completely  absorbed  by  blue 
glass  of  suflicient  thickness.  This  test  for  sodium  is  very 
delicate,  and  is  not  masked  by  even  a  considerable  pro- 
portion of  any  other  metal,  except  copper  and  calcium. 
The  presence  of  a  very  large  proportion  of  potassium 
may  conceal  the  sodium  reaction.  In  that  case,  green  glass 
will  absorb  the  violet  rays  of  the  potassium  flame,  but 
will  not  aflect  the  colored  rays  produced  by  the  sodium. 

Quantitative  estimation. — a.  Sodium,  like  potassium, 
may  be  weighed  as  chloride  or  as  sulphate,  on  evaporat- 
ing the  solution  to  dryness,  from  which  all  other  acids 
except  hydrochloric  or  sulphuric  have  been  removed  by 
the  methods  described  in  each  special  case. 

The  operations  of  evaporation  and  ignition  may  be 
conducted  precisely  as  directed  for  the  treatment  of  the 
corresponding  potassium  compounds  (§  44),  except  that 
no  provision  need  be  made  to  guard  against  loss  by  the 
decrepitation  of  the  sodic  sulphate. 

Sodic  sulphate,  Na^SO^,  contains  32.39"  [^  of  sodium  or 
43.66°|„  of  soda,  ISTa^O.  Sodic  chloride  contains  39.32"  |„ 
of  sodium. 

h.  If  potassium  is  present,  the  two  metals  being  con- 
verted into  chlorides,  ascertain  the  amount  of  the  same 
by  evaporation  to  dryness  and  weighing  the  residue  after 
gentle  ignition,  as  directed  for  the  treatment  of  potassic 
chloride  (§  44,  a),  and  then  determine  the  amount  of  po- 
tassic chloride  in  this  mixture,  with  the  aid  of  platinic 
chloride,  as  directed  under  potassium  (§  44,  c).  The  dif- 
ference between  the  sum  of  the  two  chlorides  and  the 
amount  of  potassic  chloride  will  give  the  sodic  chloride. 

In   this  separation,  enough  platinic  chloride  must  be 


§  46.     SODIUM.  53 

added  to  convert  Tjoth  the  potassium  and  the  sodium  into 
the  platinic  compounds,  and  the  evaporation  with  platinic 
chloride  should  not  be  carried  to  complete  dryness,  so  as 
to  avoid  expelling  the  water  of  crystallization  of  the  so- 
dic  salt.  The  filtrate  from  the  potassic  salt  should  have  a 
deep  yellow  color,  and  the  salt,  when  examined  with  the 
magnifier,  should  be  seen  to  consist  only  of  yellow  octa- 
hedral crystals  or  a  yellow  granular  poAvder. 

c.  If  sul23huric  acid  is  present  in  the  solution  containing 
sodium  and  potassium,  the  conversion  of  these  metals  into 
chlorides  may  be  effected  by  gentle  ignition  with  j^owder- 
ed  ammonic  chloride.  Evaporate  the  solution  of  the  sul- 
phates to  dryness,  mix  the  residue  with  a  little  more  than 
its  weight  of  jDure  ammonic  chloride,  heat  the  mixture 
gently  as  long  as  fumes  are  evolved,  and  weigh ;  add  more 
ammonic  chloride  to  the  contents  of  the  crucible,  ignite, 
and  weigh  again,  and  repeat  this  operation  as  long  as 
there  is  any  change  in  weight. 

d.  In  case  the  quantity  of  one  metal  in  the  mixture  of 
the  chlorides  is  not  very  much  larger  than  that  of  the 
other,  they  may  be  estimated  with  accuracy  by  th*^,  indi- 
rect process.  Determine  the  chlorine  in  the  known 
weight  of  the  mixture  by  the  volumetric  process  (§  63,  ^), 
and  then  calculate  the  amount  of  potassium  and  sodium 
in  it  by  the  following  formulas,  in  which  S  =  the  weight 
of  tl^e  mixture  of  the  chlorides,  and  A  —  the  amount  of 
chlorine  contained  therein. 

Potassium  =  ^ i^n^' 

e.  If  it  is  more  convenient  to  weigh  the  metals  as  sul- 
phates, the  sulphuric  acid  may  be  determined  in  the  usual 


54  §    47.       BASES    AXD    ACIDS    WITH    KEAGENTS. 

manner  (§  59),  and  the  respective  amounts  of  sodic  and 
potassic  sulphate  estimated  by  the  following  formulas,  in 
which  X  =  the  amount  of  the  sodic  sulphate,  Y  that  of 
the  potassic  sulphate,  A  the  weight  of  the  mixed  sul- 
phates, and  S  that  of  the  sulphuric  acid  contained  therein. 

S-(A    X    0.45919) 
■^  -  0.10419.  ^        ^^      "^• 

In  determining  potassium  and  sodium  by  either  of  these 
indirect  methods,  it  is  absolutely  essential  that  all  other 
metals  be  carefully  removed. 

AMMONIUM.     NH4    18.      AMMONIA.    NH3. 

47.  All  the  salts  of  ammonium  are  either  volatilized  by 
heat  or  decomposed  Avith  expulsion  of  the  ammonia,  and 
their  solubility  is  the  same  as  that  of  the  potassium  salts, 
except  that  the  tartrate  is  more  'soluble. 

Reactions. — Salts  of  ammonium  behave  like  salts  of 
potassium,  with  platinic  chloride,  except  that  when  am- 
monic  platinic  chloride  is  ignited,  nothing  but  metallic 
platinum  is  left  behind. 

When  salts  of  ammonium  are  gently  heated  with  baric 
or  sodic  hydrate,  ammonia  is  expelled  and  gives  a  blue 
color  to  a  piece  of  moistened  red  litmus-paper  held  in  the 
tube  above  the  liquid,  or  a  brown  color  to  a  piece  of  tur- 
meric'i^aper.  To  make  this  reaction  as  delicate  as  jDossi- 
ble,  put  the  substance  to  be  tested  in  a  small  beaker,  with 
baric  or  calcic  hydrate  in  a  dry  foim,  moisten  the  mixture 
with  water,  cover  the  beaker  with  a  watch-glass  on  the 
under  side  of  Avhicli  is  a  slip  of  the  moistened  test-paper, 
and  heat  the  whole  gently.  Sooner  or  later,  the  presence 
of  ammonium  will  be  manifested  by  a  change  in  the  color 
of  the  paper,  if  any  is  present  in  the  substance. 

The  test  is  a  delicate  one,  as  thus  performed,  and  none 
of  the  metals  interfere  with  it,  if  present. 


§    47.       AMMONIUM.  55 

A  still  more  sensitive  test  is  that  known  as  Nessler's. 
When  a  mixture  of  solution  of  mercuric  iodide  in  potassic 
iodide,  and  potassic  hydrate,  is  added  to  a  solution  con- 
taining ammonium,  a  light  or  reddish-brown  precipitate 
is  obtained,  NHg  J.  To  make  this  test  still  more  delicate, 
as  in  the  case  of  an  exceedingly  dilute  solution  of  the  am- 
moniacal  salt,  add  25  c.c.  of  baric  hydrate  to  a  litre  of 
the  water  to  be  examined,  distil  off  ^  1^  of  the  mixture, 
and  test  the  distillate  with  the  Nessler  solution. 

If  the  solution  is  not  too  dilute,  a  good  reaction  is  ob- 
tained on  holding  a  drop  of  the  Nessler  solution,  sus- 
pended on  the  end  of  a  glass  rod,  in  the  test-tube  just 
above  a  mixture  of  the  substance  tested  and  baric  hy- 
drate ;  if  ammonium  is  present,  the  drop  is  colored  red- 
dish-brown. 

To' make  a  litre  of  the- solution  for  this  test,  and  a  solu- 
tion that  can  also  be  used  for  quantitative  purposes,  dis- 
solve 62.5  grms.  of  potassic  iodide  in  250  c.c.  of  water, 
and  add  to  this  a  concentrated  solution  of  mercuric  chlo- 
ride, until  the  precipitated  mercuric  iodide  ceases  to  be 
dissolved  on  agitation ;  then  dissolve  150  grammes  of 
caustic  potassa  in  its  own  weight  of  water,  and  add  it 
gradually  to  the  iodized  mercurial  solution,  and  finally 
the  necessary  amount  of  water  to  make  one  litre ;  let  the 
mixture  stand  8-10  days,  decant  the  clear  and  nearly 
colorless  liquid,  and  keep  it  in  well  stoppered  bottles  in  a 
dark  place. 

Qaantitatiyc  estimation. — a.  Ammonium  may  be  de- 
termined in  the  form  of  the  ammonic  platinic  chloride, 
(NHJ^PtCl^,  when  all  metals  except  sodium  (and  calcium 
and  magnesium,  Stohmann^  are  absent.  The  course  to 
be  followed  is  precisely  the  same  as  that  described  for  the 
determination  of  potassium  in  the  corresponding  manner 
(§  44,  c).  The  double  chloride  contains  7.64"  |„  of  ammonia 
(NHJ,  or  8.07°  I,  of  ammonium. 


56  §    47.       BASES    AND    ACIDS    WITH    KEAGENTS. 

h.  Ammonia  may  also  be  determined  by  expulsion 
from  the  mixture  containing  it  by  a  strong  base,  and  col- 
lecting the  product  in  a  known  quantity  of  standard  acid. 
[Schlossing^s  process.)  The  solution  to  be  examined, 
which  should  not  be  more  than  35  c.c.  in  bulk,  nor  con- 
tain more  than  0.3  grm.  of  ammonia,  is  put  in  a  shallow 
vessel,  A,  about  5  cm.  in  diameter,  which,  in  its  turn,  is 
put  on  a  plate  about  10  cm.  in  diameter,  the  bottom  of 
which  is  covered  with  mercury.  Put  10  c.c.  of  the  nor- 
mal sulphuric  acid  in  another,  and  rather  smaller,  shallow 
vessel,  B,  that  is  supported  over  A  by  a  glass  triangle ; 
then  put  about  10  c.c.  of  milk  of  lime  or  sodic  hydrate  in 
A  with  the  ammoniacal  solution,  by  means  of  a  pipette, 
and  finally  invert  a  bell-jar  or  a  weighted  beaker  over 
the  whole,  and  be  sure  that  its  rim  is  completely  immers- 
ed in  the  mercury. 

After  48  hours,  the  ammonia  will  usually  be  entirely 
expelled  from  the  substance,  and  absorbed  by  the  acid ; 
in  the  analysis  of  animal  and  vegetable  liquids,  Schulze 
found  that  three  or  four  days  were  required,  but  that  after 
the  expiration  of  that  time  the  ammonia  was  completely 
liberated.  To  test  the  matter,  lift  the  edge  of  the  bell- 
jar  or  beaker,  or  take  out  the  stopper  of  the  tubulure,  if 
the  bell-jar  has  such  an  appendage,  and  introduce  a  piece 
of  moistened  red  litmus-paper ;  this  should  retain  its  red 
color  even  if  left  for  a  considerable  time  in  the  jar. 

If  the  operation  is  finished,  titrate  the  acid  in  the  vessel 
B,  with  the  standard  solution  of  soda  ;  the  difference  be- 
tween the  number  of  cubic  centimetres  of  acid  put  into 
B  in  the  beginning,  and  the  number  of  cubic  centimetres 
of  soda  solution  required  to  neutralize  what  acid  remains 
free,  multiplied  into  0.017  grm.  will  give  the  amount  of 
ammonia  (NII3)  in  the  substance  analyzed— or,  multiplied 
into  0.026  grm.  will  give  the  amount  of  ammonic  oxide 

(Nn.),o. 

If  albuminoids  are  present  in  the  substance  examined. 


§   47.      AMMONIUM.  57 

it  is  better  to  use  freshly  ignited  magnesia,  instead  of  milk 
of  lime,  to  set  free  the  ammonia,  so  as  to  avoid  the  forma- 
tion of  the  compound  out  of  a  portion  of  the  albuminous 
matters  ( Yogel). 

c.  When  the  substance  does  not  contain,  besides  am- 
monia, nitrogenous  organic  matter  that  would  yield 
more  ammonia  on  being  heated  with  an  alkali,  the  de- 
termination may  be  more  expeditiously  performed  as  fol- 
lows. 

Weigh  the  substance  out  in  a  small  tube  about  10  mm. 
in  diameter  and  5  cm.  long,  put  it  in  a  small  flask,  A, 
containing  a  moderately  concentrated  solution  of  sodic 
hydrate  which  has  been  previously  boiled  for  a  consider- 
able time  to  expel  all  traces  of  ammonia,  and  allowed  to 
cool  again.  Freshly  ignited  magnesia  is  sometimes  used 
in  the  place  of  the  alkali.  Put  the  flask  in  an  inclined 
position  on  the  wire  gauze  over  the  lamp,  and  connect  it 
quickly  with  the  tube  of  a  small  cooling  apparatus ;  con- 
nect the  other  end  of  this  tube  by  a  good  cork  with  a 
tubulated  receiver,  J5,  through  the  tubulure  of  which 
passes  another  small  tube  that  is  bent  twice  and  carried 
to  the  bottom  of  a  small  flask,  C.  Put  into  the  receiver, 
j5,  the  larger  portion  of  50  c.c.  of  standard  sulphuric  acid 
and  the  remainder  in  the  flask  C,  and  color  the  acid  in 
both  vessels  with  a  little  cochineal;  neither  tube  that 
passes  into  JB  should  dip  into  the  liquid  contained  in  it. 
Be  sure,  now,  that  the  apparatus  is  tight  throughout,  boil 
the  contents  of  the  flask  A  gently,  and  continue  the 
boiling  for  a  little  while  after  the  drops  of  condensed 
liquid  as  they  fall  into  the  receiver  have  ceased  to  change 
the  color  of  the  acid  as  they  come  in  contact  with  it. 
Then  remove  the  lamp,  and  allow  the  contents  of  the 
flask  (7  to  flow  back  into  B ;  rinse  C  several  times  with 
cold  water,  and  allow  these  rinsins-s  to  flow  into  B  also  ; 
finally  disconnect  the  receiver  B  from  the  rest  of  the 
apparatus,  transfer  its  contents  to  a  beaker  without  any 
3* 


58  §    47.       BASES    AND    ACIDS    WITH    REAGENTS. 

loss,  titrate  the  acid  remaining  free  with  the  standard  so- 
dic  solution,  and  estimate  the  amomit  of  ammonia  in  the 
substance  analyzed,  as  directed  in  h.     {Fresenius.) 

d.  If  the  standard  acid  in  either  of  these  processes, 
h  or  c,  should  contain  but  a  very  small  amount  of  am- 
monia, instead  of  titrating  with  soda,  the  determination 
may  be  completed  more  satisfactorily  with  the  aid  of  the 
Nessler  solution,  by  preparing  a  solution  containing  an 
accurately  known  quantity  of  ammonia,  of  such  a  strength, 
that  about  equal  volumes  of  it  and  of  the  solution  con- 
taining the  unknown  amount  of  ammonia,  will  give  the 
same  shade  of  color  with  equal  small  quantities  of  this 
reagent. 

The  color  observations  in  this  process  are  best  made  in 
narrow  glass  cylinders  of  such  a  diameter  that  100  c.c.  of 
the  water  to  be  tested  form  a  stratum  about  18  cm.  deep, 
and  by  placing  these  cylinders  upon  a  sheet  of  white 
paper  near  a  window  and  looking  at  the  surface  of  the 
liquid  obliquely. 

The  amount  of  ammonia  present  in  the  solution  to  be 
examined  should  not  be  great  enough  to  give  a  precipi- 
tate with  the  reagent,  but  only  a  coloration  ;  the  best  re- 
sults are  obtained  when  there  is  not  more  than  one  milli- 
gramme of  NHg  in  100  c.c.  of  the  solution,  but  even  if  the 
solution  is  ten  times  stronger  than  this,  the  results  are 
more  accurate  than  those  obtained  by  titration  ;  it  is  im- 
portant that  the  temperature  of  the  solution  tested  should 
be  nearly  the  same  as  that  of  the  other  solution  contain- 
ing a  known  quantity  of  ammonia,  which  is  made  the 
standard  of  comparison,  and  that  neither  free  potassa  or 
soda,  nor  calcic  or  magnesic  carbonate  should  be  present. 

To  estimate  the  ammonia  in  a  solution  by  this  method, 
first  make  a  standard  solution  of  ammonic  chloride  con- 
taining 0.3147  grm.  in  one  litre,  which  is  equal  to  0.1 
grm.  of  ammonia  (NHg)  in  the  litre ;   add  1  c.c.  of  the 


§    48.      BARIUM.       §    49.       CALCIUM.  59 

standard  iodized  mercurial  solution  to  100  or  150  c.c.  of 
the  distillate,  obtained  in  h  or  c,  or  to  any  clear  and  color- 
less solution  containing  ammonia ;  put  in  another  test- 
tube,  containing  about  100  c.c.  of  water,  as  much  of  the 
standard  solution  of  ammonic  chloride  as  is  thought  nec- 
essary to  give  the  same  shade  of  color  with  the  test- 
liquid,  make  the  volume  of  this  mixture  the  same  as 
of  the  other,  by  addition  of  water,  add  1  c.c.  of  the 
iodized  mercurial  solution,  let  stand  ten  minutes,  and  then 
compare  shades  of  color ;  if  not  alike,  make  another  more 
or  less  diluted  portion  of  the  standard  ammonic  solution, 
according  as  the  shade  of  color  of  the  first  was  too  dark 
or  too  light,  and  repeat  the  test..     {W.  A.  Miller.) 

BARIUM.     Ba.     137. 

48.  Compounds  o.  barium  with  sulphuric,  oxalic,  car- 
bonic, phosphoric,  tartaric,  and  silicic  acids,  and  with  flu- 
orine, are  insoluble  or  sparingly  soluble  in  water.  The 
sulphate  and  silicate  are  insoluble  in  acids. 

Reactions* — Sulphuric  acid  and  all  soluble  sulphates 
produce,  even  in  very  dilute  solutions  of  barium  salts,  a 
finely  pulverulent  precipitate  of  baric  sulphate,  BaSO^, 
insoluble  in  acids,  except  when  hot  and  concentrated,  and 
even  then  but  very  sparingly  soluble.  This  sulphate  is 
slightly  decomposed  when  boiled  with  a  solution  of  sodic 
carbonate,  but  is  not  changed  at  all  if  a  soluble  sulphate 
is  mixed  with  the  carbonate. 

CALCIUM.     Ca.    40. 

49.  Compounds  of  calcium  with  oxalic,  carbonic,  phos- 
phoric, tartaric,  and  silicic  acids,  and  with  fluorine,  are 
insoluble  or  sparingly  soluble  in  water.  The  tartrate  dis- 
solves in  352  parts  of  boiling  water.  The  silicate  and 
fluoride  are  insoluble  in  acids.  Both  water  and  acids  dis- 
solve the  sulphate  in  small  quantity. 


60  §    49.       BASES    AND    ACIDS    "WITH    REAGENTS. 

Reactions* — If  dilute  sulphuric  acid  or  amnionic  sul- 
phate is  added  to  a  not  too  dilute  solution  of  a  calcic  salt, 
free  from  a  large  excess  of  strong  acids,  a  white  precipi- 
tate of  calcic  sulphate,  CaSO^,  2}Ifi,  is  formed  immedi- 
ately or  after  standing  some  time,  which  is  soluble  in  an 
excess  of  mineral  acid,  and  slightly  soluble  in  acetic  acid 
and  water. 

This  sulphate  being  much  less  soluble  in  alcohox  than 
in  water,  the  addition  of  a  quantity  of  this  reagent  about 
equal  to  the  volume  of  the  solution,  will  often  cause  the  for- 
mation of  a  precipitate,  at  least  after  standing  some  time,' 
that  would  otherwise  not  appear. 

This  precipitate  is  readily  decomposed  when  boiled 
with  a  solution  of  sodic  carbonate,  calcic  carbonate  and 
sodic  sulphate  being  formed. 

Ammonic  oxalate  gives,  even  in  very  dilute  solutions 
of  calcic  salts,  if  they  contain  no  free  mineral  acid,  a 
white  crystalline  precipitate  of  calcic  oxalate,  CaC.^O^, 
soluble  in  hydrochloric  or  nitric  acid,  and  insoluble  iu 
acetic  acid  or  a  solution  of  ammonic  chloride.  If  the  so- 
lution of  the  calcic  salt  is  very  dilute,  a  precipitate  may 
not  appear  until  after  the  mixture  has  stood  some  time. 

Quantitative  Estimation. — Calcium  is  usually  deter- 
mined as  carbonate,  CaCOg,  by  precipitation  with  am- 
nionic oxalate  and  conversion  of  the  oxalate  into  carbon- 
ate by  ignition. 

a.  1 . — If  the  salt  is  soluble  in  water  or  the  acid  is  one 
that,  like  carbonic  acid,  may  be  expelled  by  hydrochloric 
acid,  or  can  be  removed  by  evaporation  to  dryness,  like 
silicic  acid,  or  the  solution  gives  no  precipitate  with  am- 
monia, add  ammonic  oxalate  to  the  hot  solution  free  from 
any  great  excess  of  acid,  and  then  ammonic  hydrate  imtil 
the  liquid,  after  being  ivell  stirred,  gives  off  an  ammoni- 
acal  odor,  let  the  mixture  stand  in  a  waiTQ  place  12  hours, 
decant  the  clear  liquid  into  a  filter,  wash  the  precifJitate 


§   49.      CALCIUM.  61 

several  times  by  decantation,  and  finally  rinse  it  into  the 
filter  with  hot  water.  Ignite  the  precipitate  and  filter 
separately  (§  40,  b)^  keeping  the  filter-ash  on  the  crucible 
cover.  Keep  the  crucible  at  a  fai?it  red  heat  5  or  10 
minutes  at  the  close  of  the  ignition ;  at  no  time  should  it 
be  heated  to  a  higher  temperature  than  this ;  during  this 
short  ignition  lift  the  cover  of  the  crucible  a  few  times. 

After  -weighing,  moisten  the  contents  of  the  crucible 
with  a  little  water  and  apply  a  piece  of  turmeric-paper 
to  the  moist  mass  ;  if  the  paper  is  turned  brown,  rinse  it 
off  with  a  very  small  quantity  of  water,  put  a  small 
lump  of  ammonic  carbonate  into  the  crucible,  heat  the 
crucible  over  the  water-bath  until  its  contents  are  dry 
again,  ignite  gently,  and  weigh  again ;  repeat  this  opera- 
tion with  fresh  portions  of  ammonic  carbonate,  and  igni- 
tion, as  long  as  there  is  any  change  in  weight.  The 
change  of  color  in  the  turmeric-paper  showed  that  the 
first  ignition  was  carried  too  far,  so  as  to  expel  some  of 
the  carbonic  acid,  and  leave  calcic  oxide.     {M'esenius.) 

The  residue  of  calcic  carbonate  contains  40  "j^  of  calci- 
um or  56  °  Iq  of  calcic  oxide  or  lime. 

2.  If  a  blast-lamp  is  at  hand,  or  a  gas  blow^pipe,  it  is 
best  to  ignite  the  precipitate  of  calcic  oxalate  10  minutes 
to  an  incipient  white  heat,  after  the  usual  ignition  to  a  red 
heat  over  the  common  lamp ;  in  this  way  all  the  calcic 
carbonate  will  be  converted  into  calcic  oxide,  which  may 
be  weighed  as  such ;  no  testing  of  the  ignited  residue  is 
necessary,  and  moreover  the  filter  may  be  burned  with 
the  precipitate. 

3.  Instead  of  igniting  the  precipitate  of  ammonic  oxa- 
late, after  it  has  been  well  washed  in  the  usual  manner, 
dissolve  it  in  dilute  hydrochloric  acid  while  yet  moist, 
add  water  in  such  a  quantity  that  the  ratio  between  the 
oxalic  acid  and  the  water  will  be  about  1  :  400  or  500, 
a^  to  this  6-8  c.c^  of  concentrated  sulphuric  acid,  and 
then  estimate  the  oxalic  acid  in  this  solution  with  the  aid 


62  50.       BASES    AXD    ACIDS    WITH    IlEAGENTS. 

of  the  standard  permanganate  solution,  as  directed  in 
§  69,  a.  This  method  yields  results  that  are  hardly  less 
accurate,  if  any  at  all,  than  the  other  two  already  de- 
scribed. For  each  equivalent  of  oxalic  acid  found,  ex- 
pressed in  milligrammes^  reckon  one  equivalent  of  lime, 
similarly  expressed,  or  0.028  grm. 

If  the  amount  of  calcic  oxalate  in  the  filter  is  very 
small,  it  may  be  converted  into  sulphate  by  ignition  with 
pure  ammonic  sulphate,  and  the  lime  weighed  as  sulphate, 
containing  41.18  "1^  of  lime. 

h.  If  the  acid  in  combination  with  the  lime  is  one  that, 
like  phosphoric  acid,  cannot  be  readily  removed,  add  am- 
monia until  a  permanent  precipitate  just  begins  to  appear, 
dissolve  this  by  adding  a  few  drops  of  hydrochloric  acid, 
add  ammonic  oxalate  in  excess,  then  sodic  acetate,  and 
proceed  as  in  a  with  the  precipitated  calcic  oxalate. 

MAGNESIUM.     Mg.     24. 

50t  Compounds  of  magnesium  with  i)hosphoric,  car- 
bonic, oxalic,  and  silicic  acids,  and  with  fluorine,  are  in- 
soluble or  sparingly  soluble  in  water.  The  silicate  and 
fluoride  are  insoluble  in  acids. 

Reactions* — The  carbonate  is  not  precipitated  from  so- 
lutions of  magnesic  salts  containing  much  ammonic  chlo- 
ride, on  addition  of  an  alkaline  carbonate. 

Hydric  disodic  phosphate  produces  a  white  precipitate 
of  ammonio-magnesic  phosphate,  MgNH^PO^,  in  solutions 
of  magnesic  salts  containing  ammonic  salts.  The  precipi- 
tate, at  first  flocculent,  if  at  all  abundant,  becomes  more 
granular  and  crystalline  after  standing  some  time,  or  after 
violent  agitation  of  the  liquid  containing  it.  If  the  solu- 
tion of  the  magnesic  salt  is  very  dilute,  the  precipitate 
may  not  appear  for  some  hours,  and  then  it  is  crystalline 
and  adheres  to  the  sides  of  the  tube  ;  if,  before  the  solu- 
tion was  set  aside,  it  was  stirred  with  a  glass  rod,  and' the 


50.       MAGNESIUM.  63 

walls  of  the  tube  rubbed  here  and  there  with  the  rod,  the 
precipitate  is  deposited  along  these  lines,  producing  the 
appearance  of  white  streaks  on  the  glass. 

Even  in  concentrated  solutions  containing  magnesium 
and  ammonic  chloride  and  sodic  phosphate,  the  whole  of 
the  ammonio-magnesic  phosphate  is  not  deposited  until 
after  long  standing ;  hence,  if  the  first  precipitate  pro- 
duced on  adding  the  reagent  is  filtered  out,  and  the  clear 
filtrate  stirred  and  set  aside,  a  fresh  precipitation  will  take 
place,  and  partly  on  the  walls  of  the  tube  in  the  manner 
described  above. 

Quantitative  estimation. — Magnesium  is  usually  deter- 
mined  as  pyrophosj^hate,  Mg^P^O^. 

a.  To  the  solution  of  the  magnesic  salt  add  a  consider- 
able quantity  of  ammonic  chloride,  and  then  ammonia  in 
slight  excess ;  if  this  ammonia  causes  the  formation  of  a 
precipitate,  add  enough  more  ammonic  chloride  to  dis- 
solve it ;  then  add  hydric  disodic  phosphate,  as  long  as  a 
precipitate  is  formed,  stir  the  mixture  well,  with  care  not 
to  touch  the  sides  of  the  beaker  with  the  rod,  cover  the 
beaker  carefully,  and  let  it  stand  with  its  contents  12 
hours  without  applying  heat ;  decant  the  clear  liquid 
through  the  filter,  rinse  the  contents  of  the  beaker  into 
the  filter  with  portions  of  the  first  filtrate,  and  wash  the 
contents  of  the  filter  with  a  diluted  ammonia  water 
containing  one  part  of  ammonia  water  of  0.96  Sp.  Gr. 
and  three  of  water,  until  the  last  five  drops  of  the  wash- 
ings give  no  opalescence  with  very  dilute  nitric  acid  con- 
taining argentic  nitrate. 

Ignite  the  precipitate  and  filter  separately.  Rose  rec- 
ommends to  ignite  the  precipitate  for  a  short  time  in  a 
porcelain  crucible  over  the  blast-lamp ;  in  this  way  it  is 
obtained  quite  white. 

Add  0.002  grm.  to  the  residue  of  magnesic  phosphate 
for  every  110  c.c.  of  the  filtrate  from  the  precipitate  (but 


64  50.       BASES   AND   ACIDS    WITH    REAGENTS. 

not  the  washings),  to  compensate  for  the  solubility  of  the 
salt  in  the  ammoniacal  solution  in  which  it  was  precipi- 
tated.    [Fresenius.) 

The  residue  contains  36.04"  1^  of  magnesic  oxide  or 
magnesia,  MgO. 

If  the  solution  containing  the  magnesium  is  strongly- 
acid.  Rose  recommends  that  the  sodic  phosphate  be  added 
first,  and  then  a  sufficient  quantity  of  ammonia  to  super- 
saturate the  acid ;  thus  he  prevents  the  formation  of  any 
hydrated  magnesic  oxide  that  is  liable  to  be  precipitated 
with  the  phosphate  and  make  it  impure. 

h.  Separation  of  Calcium  and  Magnesium. — This  is 
effected  with  ammonic  oxalate  in  the  presence  of  am- 
monic  chloride,  and  ammonia  in  slight  excess.  Add  the 
ammonic  chloride  and  ammonia  as  directed  above  in  . ', 
and  then  ammonic  oxalate ;  this  last  reagent  must  be 
added  in  slight  excess,  after  it  has  ceased  to  give  any 
further  precipitate  of  calcic  oxalate,  in  order  to  convert 
all  the  magnesium  into  oxalate.  Let  the  •mixture  stand 
12  hours  in  a  moderately  warm  place,  decant  the  clear 
liquid  into  the  filter,  wash  the  precipitate  in  the  beaker 
once  with  water,  decant  the  washings,  dissolve  the  pre- 
cipitate in  a  little  dilute  hydrochloric  acid,  add  ammonia 
in  slight  excess,  and  ammonic  oxalate ;  let  the  mixture 
stand  until  the  precipitate  has  completely  subsided,  then 
filter  through  the  same  filter  as  before,  and  wash.  The 
first  filtrate  has  the  larger  portion  of  the  magnesium  in 
it ;  the  second,  the  rest. 

Acidify  the  second  filtrate,  and  concentrate  that  and 
the  washings  by  evaporation,  add  the  residue  to  the  first 
filtrate,  and  precipitate  magnesium  in  this  solution  as 
phosphate.  Treat  the  precipitate  of  calcic  oxalate  on  the 
filter  as  directed  in  §  49. 

If,  in  the  filtrate  from  the  calcic  oxalate,  there  is  a 
great  excess  of  ammonic  salts,  it  will  be  safer  to  evapo- 
rate the  solution  to  dryness  and  expel  them  by  ignition, 


§    51.       ALUMINIUM.  65 

dissolve  the  residue  in  water  acidified  with  hydrochloric 
acid,  filter  if  necessary,  and  then  to  precipitate  the  mag- 
nesium in  the  usual  manner  with  hydric  disodic  phosphate. 

c.  If  but  little  calcium  is  mixed  with  considerable  mag- 
nesium in  the  substance  to  be  analyzed,  evaporate  the 
solution  to  dryness,  and  ignite  the  residue  gently  to  ex- 
pel ammoniacal  salts  completely,  dissolve  this  residue  in  a 
very  little  water  mixed  with  a  few  drops  of  hydrochloric 
acid,  add  strong  alcohol  and  a  slight  excess  of  pure  con- 
centrated sulphuric  acid,  and  digest  the  mixture  in  the 
cold  several  hours.  Collect  the  precipitated  calcic  sul- 
phate on  the  filter,  wash  it  first  with  almost  absolute  al- 
cohol and  finally  with  alcohol  of  about  40  "  |^,  dry,  ignite 
and  weigh. 

Expel  the  alcohol  from  the  filtrate  and  washings  by 
heat,  and  determine  magnesium  in  the  usual  manner  with 
sodio  phosphate. 

ALUMINIUM.     Al.     27.5. 

51  •  Compounds  of  aluminium  with  phosphoric  and 
silicic  acids,  and  fluorine,  are  insohible  in  water.  The 
silicate  is  insoluble  in  acids. 

Reactions. — Solutions  containing  aluminium  give  a  pre- 
cipitate, Al203,3H20,  or  AlJIgO^,  with  ammonic  or  sodic 
hydrate ;  the  precipitate  is  dissolved  in  an  excess  of  the 
latter  reagent,  but  not  in  the  former. 

When  a  compound  of  aluminium  is  fused  on  platinum 
foil  with  four  or  five  times  its  bulk  of  sodic  and  potassic 
carbonate,  the  fused  mass  dissolved  in  a  very  little  water, 
and  the  solution  filtered  if  necessary,  nitric  acid  added  to 
the  filtrate  carefully  until  effervescence  ceases,  and  then  a 
fcAV  drops  of  ammonia  until  the  solution  emits  a  faint 
odor  of  the  reagent,  a  white  flocculent  precipitate  appears, 
at  once,  or  after  standing  some  time ;  it  will  appear  soon- 
er, or  be  more  readily  perceiyed,  on  heating  the  liquid 
gently  for  a  time. 


66  52.       BASES    AND    ACIDS    WITH    IIEAGE2JTS. 

QuantitatiYC  estimation. — Aluminium  is  always  weigh- 
ed as  sesquioxide,  Al^Og. 

To  the  not  too  dilute  hot  solution  add  a  fourth  or  a 
third  of  its  volume  of  ammonic  chloride,  if  not  already- 
present,  and  then  ammonic  hydrate  until  a  faint  odor  of 
ammonia  is  perceptible  after  vigorous  stirring  ;  heat  the 
mixture  almost  to  boiling  nntil  no  more  ammonia  is  given 
off,  let  it  stand  a  few  hours  in  a  moderately  warm  place, 
decant  the  clear  liquid  through  the  filter,  wash  the  pre- 
cipitate two  or  three  times  Avith  hot  water,  by  decanta- 
tion,  transfer  the  whole  to  the  filter,  and  wash  it  until  the 
washings  leave  no  fixed  residue  on  platinum  foil ;  if  the 
solution  contained  sulphuric  acid  in  notable  quantity,  it 
will  be  best  to  dissolve  this  first  precipitate  in  dilute  hy- 
drochloric acid,  and  re-precipitate  the  aluminic  hydrate 
with  ammonia,  as  above.  Dry  the  precipitate  very  thor- 
oughly, and  ignite  it  gently  at  first,  and  carry  the  heat  to 
a  full  red,  finally. 

The  residue  is  pure  alumina. 

IRON.     Fe.    56. 

52.  Compounds  of  iron  with  carbonic,  phosphoric, 
oxalic,  and  silicic  acids,  and  sulphur,  are  insoluble  in  water ; 
the  silicate  is  insoluble  in  acids. 

Ferric  salts  give  a  yellowish-red  color  to  solutions  con- 
taining them  in  notable  quantity. 

Reactions. — Solutions  of  ferrous  and  ferric  salts  give 
precipitates,  FeO,  H,0,  or  FeH^,  and  2Fe,03,  3H,0  or 
Fe^HgOg,  with  ammonic  or  sodic  hydrate ;  the  ferrous  salts, 
however,  give  no  precipitate  with  ammonia  in  the  presence 
of  ammonic  salts.  These  precipitates  are  insoluble  in  ex- 
cess of  the  precipitant.  The  precipitate  produced  in  so- 
lutions of  pure  ferrous  salts  is  white  j  in  solutions  of 
ferric  salts,  reddish-brown. 

Solutions  of  ferrous  salts  give  a  blue  precipitate  with 


§  52.     IRON.  67 

potassic  ferricyanide ;  ferric  salts  give  no  precipitate  with 
this  reagent. 

Ferric  salts  give  a  deep  red  color  with  potassic  sulpho- 
cyanate ;  this  reaction  is  exceedingly  delicate.  Nitric 
acid  causes  the  color  to  disappear  after  a  while,  and  am- 
nionic hydrate  destroys  it  immediately.  Ferrous  salts 
give  no  color  with  this  reagent. 

Ferrous  salts  are  converted  into  ferric  compounds  when 
heated  with  nitric  acid. 

Quantitative  estimation. — Iron  may  be  determined  by 
a  gravimetric  or  a  volumetric  process.  In  the  former 
case  it  is  weighed  as  sesquioxide,  Fe^Og. 

a.  Add  ammonic  hydrate  in  excess  to  the  hot  solution, 
in  which  the  iron  has  been  completely  oxidized  by  heating 
with  nitric  acid,  if  any  ferrous  oxide  was  present,  heat 
the' mixture  almost  to  boiling,  and  then  let  it  stand  imtil 
tlie  larger  part  of  the  liquid  can  be  decanted  into  the  fil- 
ter ;  wash  the  precipitate  several  times  by  decantation, 
and  afterwards  on  the  filter,  until  a  droj)  of  the  washings 
leaves  no  residue  on  evaporation  on  platinum  foil,  and 
ignite  the  precipitate  and  filter  separately.  The  residue 
is  pure  ferric  oxide,  and  contains  70"!  ^  of  iron. 

If  the  substance  analyzed  contained  silica,  this  precipi- 
tate is  liable  to  be  contaminated  with  it,  and  should  be 
digested  with  concentrated  hydrochloric  acid,  after  hav- 
ing been  gently  ignited  ;  if  silica  is  present,  it  will  remain 
undissolved,  and  may  be  filtered  out  and  weighed. 

h.  The  volumetric  process,  with  potassic  permanganate, 
is  particularly  convenient  for  the  determination  of  iron 
in  the  presence  of  aluminium.  The  iron  is  converted  into 
a  ferrous  salt,  and  then  it  is  ascertained  how  much  of  a 
solution  of  permanganate  of  known  strength  is  required, 
to  oxidize  the  ferrous  to  a  ferric  salt. 

To  make  the  solution  of  permanganate,  dissolve  about 
8  grms.  of  the  crystallized  potassic  permanganate  of  the 


68  §    52.       BASES    AND    ACIDS   WITH    REAGENTS. 

druggists  in  one  litre  of  water ;  as  this  solution  is  changed 
by  exposure  to  the  air,  its  strength  must  be  determined 
from  time  to  time,  and  the  oftener,  the  more  imperfectly 
it  is  protected  from  such  exposure. 

To  determine  its  strength,  weigh  out  accurately  about 
1.4  grms.  of  ammonio-ferrous  sulphate,  dissolve  the  salt 
in  about  200  c.c.  of  distilled  water,  to  which  about  20  c.c. 
of  dilute  sulphuric  acid  have  been  added.  To  protect  the 
salt  more  completely  from  oxidation  while  the  solution  is 
taking  place,  heat  it  with  a  part  of  the  water  in  a  small 
flask  closed  by  a  cork  through  which  two  short  glass 
tubes  pass ;  fasten  the  flask  in  an  inclined  position  in  a 
retort-holder,  and  heat  its  contents  while  a  slow  current 
of  carbonic  acid  is  conducted  through  the  upper  part  of 
it.  When  the  solution  is  completed,  let  the  liquid  cool  in 
the  current  of  carbonic  acid,  transfer  it  quickly  to  a  beak- 
er or  a  larger  flask,  rmse  the  flask  out  with  the  rest  of 
the  water,  set  the  vessel  over  white  paper,  and  immedi- 
ately begin  to  add  the  solution  of  permanganate  from  a 
burette,  with  constant  stirring  of  the  liquid.  At  first, 
the  red  drops  disappear  the  instant  that  they  come  in 
contact  with  the  solution,  and  the  latter  gradually  takes 
a  yellowish  tint ;  add  the  permanganate  more  and  more 
carefully  as  the  drops  begin  to  disappear  less  readily,  and 
stop  when  the  last  drop  gives  an  unmistakable  reddish 
color  to  the  whole  liquid. 

Ammonio-ferrous  sulj)hate  contains  just  one-seventh  of 
its  weiglit  of  iron,  and  hence  the  amount  of  permanganic 
solution  used  in  this  trial  will  convert  a  weight  of 
iron  from  ferrous  to  ferric  oxide,  equal  to  one-seventh  of 
the  weight  of  tlie  salt  taken. 

The  concentration  of  the  solution  of  permanganate 
should  be  such,  that  from  20  to  30  c.c.  is  required  for  1.4 
grms.  of  ammonio-ferrous  sulphate,  or  0.2  grm.  of  metal- 
lic iron. 

Now,  to  determine  iron  by  this  process  the  ferric  salt 


§  52.     iRoif.  69 

must  be  in  the  form  of  a  sulphate  or  a  chloride,  and  the 
solution  should  contain  about  0.5  grm.  of  iron  and  an 
excess  of  free  sulphuric  or  hydrochloric  acid  and  as  little 
nitric  acid  as  possible ;  heat  the  solution  in  a  small,  long- 
necked  flask  placed  in  an  inclined  position,  drop  in  a  few- 
pieces  of  pure  zinc,  and  conduct  carbonic  acid  through 
the  flask  in  the  same  manner  as  described  above,  for  dis- 
solving the  ferrous  salt ;  the  ferric  compound  is  reduced 
to  a  ferrous  salt  by  the  zinc,  with  the  evolution  of  hydro- 
gen. When  the  solution  is  decolorized,  and  all  the  zinc 
is  dissolved,  cool  the  liquid  as  quickly  as  possible  by  im- 
mersing the  flask  in  cold  w^ater,  while  carbonic  acid  is 
still  passing  through,  transfer  the  solution  to  a  beaker, 
rinse  the  flask  into  the  beaker  with  a  considerable  quanti- 
ty of  w^ater,  and  dilute  the  solution  until  it  contains  about 
200  c.c.  for  every  0.2  grm.  of  iron  supposed  to  be  present ; 
the  solution  must  be  more  largely  diluted  if  the  salt  was 
a  chloride,  or  w^as  dissolved  in  hydrochloric  acid,  instead 
of  sulphuric. 

To  this  solution  add  the  solution  of  permanganate  in 
the  same  manner  as  directed  above,  for  the  treatment  of 
the  ferrous  salt. 

The  amount  of  iron  m  the  quantity  of  solution  taken 
will  be  given  by  the  proportion 

C  :  F  =  C^  :  X 
7 
in  which  C  =  the  number  of  cubic  centimetres  of  per- 
manganic solution  used  in  the  trial  with  the  known  quan- 
tity of  ferrous  salt,  F  =  the  weight  of  the  ferrous  salt 
taken,  C  =  the  number  of  cubic  centimetres  of  perman- 
ganic solution  used  in  the  trial  with  the  substance  exam- 
ined, and  X  =  the  amount  of  iron  therein. 

The  solution  of  potassic  permanganate  is  most  con- 
veniently kept  in  a  bottle  provided  with  an  ordinary 
w^ashing-bottle  arrangement  for  filling  the  burette  from 
it  •  then  the  bottle  need  not  be  opened  until  empty,  no 


70  52.       BASES    AND    ACIDS    WITH    EEAGENTS. 

dust  can  get  into  it,  particularly  if  the  open  end  of  the 
shorter  tube  is  closed  with  a  plug  of  cotton,  and  its 
strength  will  not  change  perceptibly  in  two  or  three 
months. 

c.  The  following  volumetric  method  of  estimating  fer- 
ric oxide  has  given  satisfactory  results  ( Oudemans^  Fre- 
seniiis's  Zeitschrift,  6,  129),  and  is  very  easily  executed. 

Prepare  a  standard  solution  of  sodic  hyposulphite,  by 
dissolving  24.8  grms.  of  the  pure  crystallized  salt  in  one 
litre  of  water;  this  gives  a  ^1,^  normal  solution,  since  248 < 
is  the  equivalent  of  the  crystallized  salt.  Determine  the 
strength  of  a  solution  of  ferric  chloride  containing  no 
traces  of  free  chlorine,  as  carefully  as  possible,  by  precipi- 
tation with  ammonia  (a). 

To  a  quantity  of  this  solution,  accurately  measured, 
containing  about  0.2  grm.  of  iron,  add  a  littl6  hydrochlo- 
ric acid,  one  or  two  drops  of  a  concentrated  solution  of 
cupric  sulphate,  and  the  same  quantity  of  potassic  sulpho- 
cyanate  ;  heat  this  blood-red  liquid  to  about  40°  C,  and 
allow  the  standard  solution  of  hyposulphite  to  flow  from 
a  burette  into  it  Avith  constant  stirring,  until  the  red  color 
disappears,  leaving  a  clear,  colorless  liquid  ;  towards  the 
end  of  the  operation,  when  the  color  of  the  solution  has 
become  quite  pale,  wait  a  few  seconds  between  each  ad- 
dition of  a  few  drops  of  the  hyposulphite.  Divide  the 
quantity  of  ferric  oxide  corresponding  to  the  amount  of 
ferric  chloride  taken,  by  the  number  of  cubic  centimetres 
of  the  solution  of  hyposulphite  required  in  this  trial,  and 
the  quotient  will  give  the  amount  of  ferric  oxide  which 
the  sodic  hyposulphite  in  one  cubic  centimetre  of  the 
standard  solution  is  able  to  reduce  to  protoxide. 

Having  in  this  way  determined  the  value  of  the  solu- 
tion of  hyposulphite  with  reference  to  ferric  oxide,  this 
oxide  may  be  determined  in  any  solution  containing  it  or 
the   corresponding    chloride,   in    the    manner  described 


§    53.       MANGANESE.  71 

above ;  the  solution  should  contain  no  free  chlorine  or  ni- 
tric acid. 

The  standard  solution  of  hyposulphite  should  be  care- 
fully protected  from  the  light,  and  the  determination  of 
its  strength  should  be  repeated  from  time  to  time  by  com- 
parison with  a  portion  of  the  solution  of  ferric  chloride 
of  known  strength,  as  above. 

MANGANESE.     Mn.  55. 

53 •  Compounds  of  manganese  with  phosphoric,  car- 
bonic, oxalic,  and  silicic  acids,  and  sulphur,  fluorine,  and 
cyanogen,  are  insoluble  or  sparingly  soluble  in  water. 
The  silicate  is  insoluble  in  acids. 

Reactions. — A  solution  containing  manganese  gives  a 
precipitate,  MnO,H20,  or  MnH^O^,  with  sodic  or  ammonic 
hydrate ;  the  presence  of  ammonic  chloride  prevents  the 
formation  of  the  precipitate  by  ammonic  hydrate ;  in  this 
way  manganese  may  be  partially  separated  from  iron  for 
qualitative  purposes. 

When  a  compound  of  manganese  is  fused  with  potassic 
and  sodic  carbonate  and  sodic  nitrate,  the  fused  mass 
takes  a  bluish-green  color,  which  can  be  masked  only  by 
the  presence  of  a  very  considerable  quantity  of  iron.  In 
case  this  large  proportion  of  iron  is  present,  it  may  be 
precipitated  by  ammonia  after  adding  considerable  am- 
monic chloride,  filtering  it  out  quickly,  and  evaporating 
the  filtrate ;  then  test  a  few  drops  of  the  concentrated 
liquid  by  fusion,  as  above. 

Quantitative  estimation. — The  manganese  is  usually 
precipitated  as  carbonate ;  when  ignited,  this  carbonate  is 
converted  into  manganous  manganic  oxide,  MugO^,  which 
is  weighed.  Heat  the  solution,  free  from  any  great  excess 
of  mineral  acid,  nearly  to  boiling  in  a  capacious  flask,  add 
sodic  carbonate  very  slowly  until  it  is  in  excess,  boil  a  few 
minutes,  and  wash  the  precipitate  by  decantation  and  on 


72  §    54.       BASES    AND   ACIDS   WITH    REAGENTS. 

the  filter;  ignite  the  filter  and  its  contents  separately. 
The  ignition  should  be  carried  to  a  full  red  heat.  The 
residue  contains  72.05"  j^  of  manganese. 

ZINC.  Zn.     65. 

54.  Compounds  of  zinc  with  phosphoric,  carbonic,  ox- 
alic,  and  silicic  acids,  and  sulphur  and  cyanogen,  are  in- 
soluble or  sparingly  soluble  in  water.  The  silicate  is 
insoluble  in  acids. 

Reactions. — Solutions  of  zincic  salts  give  a  white  pre-^ 
cipitate,  ZnO,  H^O  or  ZnH^O^,  with  sodic  or  ammonic 
hydrate,  soluble  in  excess  of  the  precipitant,  and  re-pre- 
cipitated from  this  solution  on  dilution  with  considerable 
water  and  boiling. 

Solutions  of  zincic  salts  give  a  white  flocculent  precipi- 
tate, Zn^Fe^Cyg,  with  potassic  ferrocyanide,  that  is  diffi- 
cultly soluble  in  acids. 


LEAD.     Pb.     207. 

55.  Compounds  of  lead  with  sulphuric,  phosphoric,  car- 
bonic, oxalic,  and  tartaric  acids,  and  sulphur  and  fluorine, 
are  insoluble,  or  sparingly  soluble  in  water.  The  sulphate 
and  sulphide  are  insoluble  in  dilute  acids. 

Reactions. — Solutions  of  salts  of  lead  give  a  white  pre- 
cipitate, 2PbO,  H^O  or  Pb^H^Og,  with  sodic  or  ammonic 
hydrate,  insoluble  in  excess  of  the  precij^itant. 

If  free  from  a  very  large  excess  of  strong  acid,  they 
give  a  white  precipitate,  PbSO^,  with  dilute  sulphuric 
acid,  which  appears  at  once,  or  after  some  time  if  the  so- 
lution is  very  dilute  ;  this  precipitate  is  insoluble  in  dilute 
acids,  and  is  more  insoluble  in  dilute  sulphuric  acid  than 
in  pure  water  ;  it  i^  soluble  in  a  solution  of  ammonic  tar- 
trate containing  an  excess  of  ammonia ;  if  this  solution 
is  acidified  with  acetic  acid  and  potassic  dichromate  add- 


§    56.       COPPER.       §    57.       ARSENIC.  73 

ed,  a  yellow  precipitate  of  plumbic  chromate,  PbCrO^,  is 
formed. 

Lead  is  precipitated  from  its  solutions  by  metallic  zinc 
in  the  presence  of  free  acid. 

COPPER.     Cu.     63.5. 

56.  Compounds  of  copper  with  phosphoric,  oxalic,  car- 
bonic, tartaric,  and  silicic  acids,  and  sulphur  and  cyanogen, 
are  insoluble,  or  sparingly  soluble  in  water.  The  sulphide 
and  silicate  are  insoluble  in  dilute  acids. 

Cupric  salts  give  a  blue  or  a  greenish-blue  color  to  so- 
lutions containing  them. 

Reactions* — Solutions  containing  copper  give  a  green- 
ish precipitate,  CuO,  H^O  or  CuH^O^,  with  sodic  or  am- 
monic  hydrate.  This  precipitate  is  dissolved  by  an  excess 
of  ammonic  hydrate,  giving  a  deep  blue  solution ;  the 
reaction  is  very  delicate. 

Solutions  of  copper  give  a  red  precipitate  with  potassic 
ferrocyanide,  Cu^Fe^Cyg. 

Copper  is  j^recipitated  from  its  solutions  by  zinc  in  the 
presence  of  free  sulphuric  or  hydrochloric  acid;  free 
nitric  acid  hinders  the  reduction,  but  does  not  prevent  it. 

ARSENIC.     As.     75. 

57.  When  a  solution  containing  arsenic  is  treated  with 
dilute  sulphuric  acid  and  metallic  zinc,  in  a  small  flask 
closed  with  a  cork  through  which  passes  a  glass  tube 
drawn  out  to  a  small  jet  at  the  end,  and  the  escaping  gas 
is  lighted,  after  it  has  been  evolved  long  enough  to  expel 
the  oxygen  from  the  flashy  a  bluish  flame  is  produced, 
which  deposits  black,  shiny  spots  on  a  cold  porcelain  sur- 
face. The  arsenic  was  evolved  as  arseniuretted  hydrogen, 
AsIIg.  This  reaction  is  very  delicate,  and  is  known  as 
Marsh's  test. 

4 


74  §    58.       BASES    AND    ACIDS    WITH    REAGENTS. 

ACIDS. 
SILICIC  ACID.     HaSiOg. 

58.  All  silicates  are  insoluble  in  water  and  dilute  acids, 
except  those  of  potassium  and  sodium. 

Silicates  may  be  decomposed,  and  the  metals  contained 
in  them  brought  into  a  soluble  form,  by  means  of  concen- 
trated hydrochloric  or  sulphuric  acid,  by  hydrofluoric  acid 
or  ammonic  fluoride,  or  by  fusion  with  an  alkaline  carbon- 
ate, and  subsequent  treatment  with  dilute  hydrochloric^ 
acid. 

Reactions. — If  a  solution  of  a  soluble  silicate  is  evapo- 
rated to  dryness,  after  addition  of  hydrochloric  acid,  the 
residue  gently  ignited  and  treated  with  dilute  acid,  the 
silica  remains  undissolved  in  the  form  of  a  white,  gritty 
powder. 

When  a  silicate  in  powder  is  fused  in  a  bead  of  sodic 
carbonate,  on  platinum  wire,  the  carbonic  acid  is  expelled 
by  the  silicic,  and  its  evolution  causes  the  bead  to  froth. 

If  a  very  small  fragment  of  an  insoluble  silicate  is 
fused  in  a  bead  of  phosphorus-salt,  on  platinum  wire, 
the  bases  are  dissolved  out,  and  the  silica  remains  floating 
about  in  the  bead,  retaining  the  form  of  the  original 
fragment. 

Quantitative  estimation. — Silicic  acid  is  always  weighed 
as  such. 

a.  1. — If  the  acid  is  to  be  determined  in  a  solution  or 
a  soluble  silicate,  add  an  excess  of  hydrochloric  acid  to 
the  solution,  or  the  very  finely  powdered  solid,  antt 
evaporate  the  mixture  to  dryness  on  the  water-bath  with 
frequent  stirring  to  break  up  tlie  lumps. 

If,  as  is  sometimes  the  case,  the  solution  analyzed  con- 
tains organic  matter,  or  ferrous  oxide,  add  a  few  drops  of 
nitric  acid  towards  the  close  of  the  evaporation.  If  a  solid 
is  being  treated,  the  digestion  should  be  continued,  with 


§    58.       SILICIC    ACID  75 

the  addition  of  fresh  quantities  of  acid  if  necessary,  until  no 
gritty  particles  can  be  felt  under  the  end  of  the  stirring 
rod.  Heat  the  residue  to  a  temperature  somewhat  above 
100°,  in  an  air-bath,  made  by  suspending  the  dish  on  wires 
inside  of  an  iron  dish,  so  that  there  shall  be  a  space  of 
about  12  mm.  between  the  two  at  all  points;  when  the 
whole  is  completely  dry  and  no  more  acid  fumes  escape, 
moisten  the  residue  with  concentrated  hydrochloric  acid, 
let  it  stand  half  an  hour,  add  water,  and  digest  the  mix- 
ture awhile,  wash  the  insoluble  residue  two  or  three  times 
by  decantation,  wash  well  on  the  filter,  dry,  and  ignite. 
The  residue  is  generally  pure  silicic  acid. 

All  the  bases  with  which  the  silica  was  combined  can 
be  determined  in  the  filtrate  from  it. 

2.  Sometimes  this  residue  is  mixed  wdth  sand  which  it 
may  be  desired  to  estimate. 

In  this  case  collect  the  mixture  on  a  dried  and  weighed 
filter,  dry  it  at  100°  C,  and  weigh  it ;  then  separate  it 
from  the  filter  as  completely  as  possible  without  tearing 
the  latter,  and  boil  it  Avith  several  portions  of  a  concen- 
trated solution  of  sodic  carbonate,  or  with  sodic  carbonate 
to  which  about  ^  |^  of  sodic  hydrate  has  been  added,  or 
with  sodic  hydrate  alone;  dilute  each  portion  of  the 
liquid  if  it  contained  much  free  alkali,  let  it  cool,  and 
throw  it  on  the  same  filter  from  which  the  mixture  of 
silica  and  sand  was  taken ;  finally,  transfer  the  insoluble 
sand  to  the  same  filter,  wash  it  well,  dry,  and  ignite.  If 
the  extraction  of  the  silica  was  performed  in  a  silver  dish, 
the  amount  taken  into  solution  by  the  alkaline  liquids 
may  be  estimated  also ;  for  this  purpose,  evaporate  all  the 
filtrates  and  washings  to  dryness,  after  having  added  an 
excess  of  hydrochloric  acid,  and  determine  the  silica  as 
in  a. 

3.  Sometimes,  in  agricultural  analyses,  this  residue  con- 
tains, besides  silica  and  sand,  free  carbon,  or  coal.  In 
this  case,  dry  the  whole  at  100°  and  weigh  it,  separate  it 


76  §    58.       BASES    AND    ACIDS   ^VITII    IlEAGE^TS. 

from  the  filter  as  above,  treat  it  with  the  alkaline  solu- 
tions also  in  the  same  manner,  collect  the  residue  that  is 
insoluble  in  the  alkali  on  a  dried  and  weighed  filter,  dry 
and  weigh  it,  and  finally  ignite  and  weigh  again.  The 
first  of  the  three  weighings  gives  the  total  amount  of 
silica,  sand,  and  coal,  the  second  the  sand  and  coal,  and 
the  third  the  sand  alone. 

h.  If  the  silicate  is  insoluble  in  water  or  acids,  pulverize 
it  until  an  impalpable  pow^der  is  obtained,  mix  a  weighed 
quantity  of  it,  in  a  platinum  crucible,  with  four  parts  of 
finely  powdered  j^otassic  sodic  carbonate,  as  intimately  as 
possible  by  stirring  with  a  glass  rod ;  wipe  the  glass  rod 
Avith  a  little  more  of  the  carbonate  on  a  slip  of  glazed 
paper,  and  transfer  this  from  the  paper  to  the  crucible ; 
the  latter  should  not,  with  all  its  contents,  be  more  than 
two-thirds  filled.  Cover  it  well  and  heat  at  first  moder- 
ately over  a  blast-lamp,  or,  after  imbedding  it  in  calcined 
magnesia  in  a  Hessian  crucible,  in  a  furnace ;  carry  the 
heat  gradually  to  an  intense  red  ;  after  about  20  minutes 
the  mass  will  have  ceased  to  boil  and  bubble,  and  the 
operation  is  finished.  Put  the  crucible,  when  cold,  into  a 
beaker  with'  considerable  water,  and  add  hydrochloric 
acid  gradually,  as  directed  for  the  solution  of  carbonates, 
§  36  ;  when  the  mass  is  entirely  loosened  from  the  cruci- 
ble, take  the  latter  out,  rinse  it  carefully  into  the  beaker, 
transfer  the  contents  of  the  beaker  to  a  platinum  or  a 
porcelain  dish,  evaporate  to  dryness,  and  eliminate  silicic 
acid,  as  in  a. 

c.  Of  course  potassium  and  sodium  cannot  be  deter- 
mined in  the  filtrate  from  the  silica  in  6,  since  both  metals 
have  been  added  to  the  substance  in  a  large  and  undeter- 
mined quantity. 

For  the  determination  of  these  elements  the  silicate 
must  be  decomposed  with  the  aid  of  hydrofluoric  acid  or 
a  fluoride. 


§    53.       SILICIC    ACID.  ^ 

1.  Decomposition  with  hydrofluoric  acid.— Proviae  a 

leaden  cup  about  16  cm.  in  diameter  and  16  cm.  deep 
with  a  close-fitting  cover,  with  projections  on  the  sides 
about  8  cm.  from  the  bottom,  supporting  a  perforated 
shelf,  and  with  a  shallow  tray  in  the  bottom  about  12  cm. 
in  diameter  and  3  cm.  deep,  all  made  of  lead ;  spread  a 
layer  of  finely  powdered  fluor  spar  about  12  mm.  deep, 
over  the  bottom  of  the  tray  in  the  cup,  and  mix  it  with 
enough  concentrated  sulphuric  acid  to  make  a  thin  paste ; 
put  the  shelf  in  its  place  and  on  the  shelf  a  shallow  plat- 
inum dish,  such  as  a  crucible  cover,  containing  1-2  grms. 
of  the  very  finely  j^ulverized  and  carefully  weighed  sub- 
stance, spread  over  the  surface  of  the  dish  in  as  thin  a 
layer  as  possible  and  moistened  with  sulphuric  acid ; 
put  the  cover  on  the  cup,  and  set  it  in  a  warm  place 
wliere  the  temperature  is  about  60°  or  70°  C,  and  lift 
the  cover  a  few  times  in  the  course  of  the  digestion ; 
the  evolution  of  the  hydrofluoric  acid  should  be  main- 
tained all  the  time.  After  48  hours  take  the  substance 
out,  expel  most  of  the  sulphuric  acid  by  heat,  boil  the 
residue  with  dilute  hydrochloric  acid,  and,  if  anything 
remains  undissolved,  treat  this  residue  with  hydrofluoric 
acid  in  the  same  manner  as  above  described.  The 
alkaline  metals  can  be  determined  in  this  solution  by 
hydrochloric  acid. 

2.  Decomposition  by  ammonic  fluoride. — This  method 
is  considered  by  many  to  be  easier  of  execution  and  more 
certain  in  its  results  than  the  other.  Mix  the  very  finely 
pulverized  silicate  with  4-5  times  its  weight  of  ammonic 
fluoride  in  a  platinum  dish,  moisten  the  mixture  thorough- 
ly with  concentrated  sulphuric  acid,  and  heat  the  whole 
on  the  water-bath  in  a  place  where  the  fumes  of  hydro- 
fluoric acid  will  bo  carried  oif  speedily;  after  a  time, 
when  the  evolution  of  acid  fumes  has  ceased,  moisten  the 
residue  again  with  sulphuric  acid,  and  heat  it,  directly 
over  the  lamp  at  last,  until  it  is  completely  dry  and  all 


78  §    59.       BASES    AND    ACIDS    WITH    EEAGENTS. 

the  sulphuric  acid  is  expelled ;  digest  the  residue  with 
hydrochloric  acid;  it  should  be  dissolved  completely, 
although,  if  calcium  is  2)resent,  considerable  time  may  bo 
required.  If  the  solution  is  not  complete,  the  insoluble 
j^art  should  be  treated  again  with  amnionic  fluoride. 

SULPHURIC  ACID.     112804. 

59.  The  sulphates  of  lead,  barium,  and  calcium,  are  in- 
soluble, or  difficultly  soluble,  in  water  and  dilute  acids ; 
the  last  of  the  three  is  much  the  most  soluble. 

Reactions* — Sulphuric  acid  and  solutions  of  sulphates 
give  a  finely  pulverulent  2)recipitate,  BaSO^,  with  baric, 
chloride,  insoluble  in  water  or  dilute  acids  ;  the  reaction 
is  very  delicate. 

Quantitative  estimation. — This  acid  is  always  de- 
termined as  baric  sulphate,  BaSO^.  Heat  the  slightly 
acid  solution  nearly  to  boiling,  and  add  a  hot  solution 
of  baric  chloride  as  long  as  a  precipitate  is  formed ; 
let  the  mixture  stand  until  the  j^recipitate  settles,  and 
wash  the  latter  by  decantation,  until  the  washings 
give  no  reaction  for  barium  with  sulphuric  acid ;  then 
pour  40  or  50  c.c.  of  the  solution  of  cupric  acetate 
(§  9)  over  the  precipitate  in  the  beaker,  add  some  water 
and  so  much  acetic  acid  that,  after  digestion  for  10 
or  15  minutes  at  a  temperature  very  near  to  boiling,  no 
basic  cupric  salt  separates  from  the  solution ;  if  any  does 
appear,  dissolve  it  by  adding  mere  acetic  acid ;  stir  the 
mixture  constantly  during  the  digestion.  Filter,  wash 
the  precipitate  with  hot  water,  and,  if  the  filter  is  still 
colored  blue,  moisten  it  with  a  little  dilute  hydrochloric 
acid  and  wash  with  more  water,  until  the  washings  give 
no  reaction  for  copper  with  potassic  ferrocyanide.  Ignite 
the  precipitate  and  filter  separately.  The  residue  con- 
tains 34.31"  |„  of  sulphuric  anhydride,  SO3,  or  13.73°  |„  of 
sulphur. 


§    60.       CARBONIC    ACID.  79 

Unless  the  precipitated  baric  sulphate  is  washed,  as 
above  directed,  with  a  solution  of  cupric  acetate,  the  re- 
sult of  the  analysis  may  be  very  unreliable,  particularly 
if  notable  quantities  of  nitrates  or  alkaline  salts  were 
present. 

CAEBONIC  ACID  OR  ANHYDRIDE.     CO2.    44. 

60«  Carbonates  of  all  except  the  alkaline  metals  are 
insoluble,  or  sparingly  soluble  in  water ;  all  carbonates, 
without  exception,  are  dissolved  by  dilute  acids,  with  the 
expulsion  of  carbonic  anhydride,  CO^. 

Reaction. — When  dilute  nitric  or  hydrochloric  acid  is 
added  to  a  carbonate,  whether  a  solid  or  in  solution,  the 
anhydride  is  expelled  with  effervescence,  and  if  a  drop 
of  lime-water,  suspended  on  the  end  of  a  glass  rod,  is 
held  in  the  tube  just  above  tlie  liquid,  it  is  made  turbid 
by  the  formation  of  insoluble  calcic  carbonate. 

Quantitative  estimation. — Carbonic  acid  is  usually 
estimated  by  the  loss  of  weight  suffered  by  the  carbonate 
on  treating  it  with  a  stronger  acid,  or  by  collecting  and 
weighing  the  expelled  anhydride  itself. 

a.  For  the  first  method  a  convenient  form  of  an  ap- 
paratus is  represented  in  the  adjoining  figure. 

The  carbonate  is  weighed  in  the  flask  A  and  water  is 
added.  B  is  nearly  filled  with 
nitric  acid ;  C  contains  fused  calcic 
chloride  to  absorb  the^  moisture 
from  the  carbonic  acid  as  it  passes 
out,  and  so  retain  it  in  the  appara- 
tus. The  apparatus  being  put  to- 
gether, with  water  enough  in  the 
flask  A  to  cover  the  mouth  of  the 
tube  leading  from  B^  close  the 
mouth  of  the  tube  at  e  with  the  finger,  and  suck  a 
very  small  quantity  of  air  out  at  d;  on  letting  air  in 


Fiff.  3. 


80  §    60.       BASES    AND    ACIDS    WITH    KEAGENTS. 

again  at  c?,  the  water  will  rise  in  the  tube  leading  from 
A  to  -S,  and,  if  the  apparatus  is  tight,  will  remain  at  a 
stationary  level  above  that  of  the  water  outside  of  the 
tube.  Now,  weigh  the  whole  apparatus,  apply  suction  at 
d  to  cause  a  little  nitric  acid  to  flow  over  into  A  from 
time  to  time,  and  in  this  manner  keep  up  a  slow  evolution 
of  carbonic  acid ;  when  all  the  carbonate  is  decomposed, 
and  all  the  nitric  acid  transferred  to  the  flask,  apply  a 
little  heat  to  the  latter ;  then,  by  suction  at  c?,  draw  air 
through  the  apparatus  as  long  as  any  acid  taste  is  jDcr- 
ceived  in  the  gas,  let  the  apparatus  cool,  and  weigh  it. 
The  air  should  be  caused  to  pass  through  a  calcic  chloride 
tube  before  it  goes  into  the  apparatus,  in  order  to  dry  it 
thoroughly. 

The  loss  of  weight  sufiered  by  the  whole  apparatus 
equals  the  carbonic  anhydride,  CO^. 

This  method,  otherwise  very  convenient,  is,  according 
to  Prof.  S.  "W.  Johnson,  (American  Journal  of  Science 
and  Arts,  Second  Series,  48,  111)  liable  to  the  objection, 
that  in  freeing  the  apparatus  completely  from  carbonic 
acid,  some  vapor  of  water  escapes  the  desiccating  materi- 
al. He  therefore  proposes  to  fill  the  apparatus  with  car- 
bonic acid  gas  before  weighing  it,  and  then  to  weigh  it 
again  as  soon  as  the  decomposition  of  the  carbonate  is 
completed ;  it  is  essential  only,  that  the  substance  under 
examination  dissolve  freely  in  cold  acid,  and  that  the 
analysis  and  weighings  be  conducted  in  an  apartment  not 
liable  to  changes  of  temperature. 

His  apparatus  may  be  closely  imitated  by  substituting 
for  the  acid  reservoir  in  the  above  figure,  another  one 
consisting  of  a  bulb  of  sufficient  size  blown  on  a  tube  of 
which  one  end,  that  passes  just  through  the  cork  in  the 
flask,  has  an  internal  diameter  of  7  mm.,  is  cut  ofl'  oblique- 
ly, and  bent  so  that,  on  inclining  the  whole  apparatus 
when  put  together,  the  acid  can  be  made  to  flow  from  the 
bulb  into  the  flask ;  the  other  end  of  this  tube  is  turned 


§    60.       CARCONIC   ACID.  81 

upwards.  Short  pieces  of  thick- walled  rubber  tubing  that 
Avill  fit  snugly  on  the  outer  termination  of  the  calcic  chlo- 
ride tube  and  the  acid  reservoir,  at  d  and  6,  are  slipped 
over  them,  and  these  rubber  tubes  are  then  provided  with 
well-fitting  stoppers  of  glass  rod  ;  all  thes3  joints  must 
be  air-tight. 

The  carbonate  is  weighed  as  usual  in  the  flask,  A,  bet- 
ter in  the  form  of  small  fragments  than  of  a  powder,  tlie 
acid  reservoir  is  nearly  filled  with  hydrochloric  acid 
(Sp.  Gr.  =  1.1),  the,  apparatus  is  j^ut  together,  and,  after 
the  glass-rod  stoppers  are  removed,  it  is.  connected  with  a 
generator  of  carbonic  acid,  and  a  rather  rapid  current  of 
vrashed  gas  is  passed  through  for  about  15  minutes,  or 
until  the  acid  in  the  reservoir  is  saturated,  and  the  air 
displaced  in  the  flask  ;  then  stop  the  opening  at  c?,  discon- 
nect-the  apparatus  from  the  generator,  and  close  the  open- 
ing at  e,  with  care  in  this  and  all  subsequent  operations  to 
handle  the  apparatus  so  as  not  to  change  its  temperature. 

Weigh  it  immediately,  loosen  the  stopper  at  J,  and  in- 
cline the  whole  so  that  the  acid  will  flow  over,  little  by 
little,  and  produce  a  slow  decomposition  of  the  carbonate. 
Close  d  again  when  the  decomposition  is  ended,  let  the 
apparatus  stand  about  15  minutes,  to  be  sure  that  it  is 
cool,  pass  well-dried  carbonic  acid  gas  in  again  for  about 
a  minute,  in  the  same  manner  as  at  first,  and  finally  weigh 
it  after  closing  d  and  e. 

h.  For  the  second  method  the  following  form  of  ai> 
paratus  is  liighly  recommended  by  Fresenius. 

In  the  apparatus  represented  by  this  figure  e  contains 
soda  lime  or  caustic  potash  in  pieces,  a  is  a  flask  of  about 
300  c.c.  capacity,  the  arm  /  of  the  first  U  tube  is  filled 
with  fused  calcic  chloride,  and  the  arm/  with  pumice-stone 
that  has  been  soaked  in  a  concentrated  solution  of  cupric 
sulphate,  dried,  and  gently  ignited  so  as  to  drive  out  the 
water  of  crystallization  of  the  salt ;  g  contains  pieces  of 
glass,  6  to  10  drops  of  concentrated  sulphuric  acid  in  the 
4* 


82 


60.       BxVSES    AXD    ACIDS    WITH    EEAGENTS. 


bottom  and  plugs  of  asbestos  in  the  upper  parts  of  both 
arms ;  A  is  '  1^  filled  with  about  20  grms.  of  coarse  grained 
soda  lime,  and  the  remaining  ^  |g  at  h'  is  filled  with  coarse- 


ly pulverized  calcic  chloride ;  the  arm  k  of  the  last  IT 
tube  contains  calcic  chloride,  and  the  arm  k'  soda  lime. 

The  carbonic  acid  evolved  in  a  is  deprived  of  its  water 
and  hydrochloric  acid  in  j^' ;  g  enables  the  operator  to 
observe  the  rapidity  of  the  flow  of  the  gas,  while  the  acid 
is  absorbed  and  weighed  in  (j  and  AA'/  the  contents  of 
kk'  prevent  carbonic  acid  and  water  from  reaching  the  U 
tube,  hh' ^  from  the  atmosphere. 

Weigh  out  the  substance  in  a,  add  water,  weigh  g  and 
hli'  together,  connect  the  various  j^arts  of  the  apparatus 
with  each  other,  and  the  little  funnel  d  with  J,  and  put  a 
few  drops  of  mercury  in  at  d  so  as  to  close  the  tube  at  i. 

Pour  the  usual  quantity  of  dilute  nitric  or  hydrochloric 
acid  in  at  f/,  and,  by  suction  at  /,  cause  a  little  of  the  acid  to 
flow  over  into  the  flask  ;  regulate  the  flow  of  tlie  gas  by 
slowly  transferring  fresh  quantities  of  acid  from  h  to  c?, 
and  applying  a  gentle  heat  to  the  contents  of  the  flask. 

When  the  carbonate  is  completely  decomposed,  fill  d 
several  times  with  hot  water  and  transfer  the  same  to  a  ; 
then,  substitute  the  calcic  chloride  tube  e  for  the  funnel  d^ 


§  61.     piiosPHomc  ACID.  83 

bring  the  contents  of  the  flas'c  to  a  gentle  boiling,  and 
continue  the  application  of  the  heat  until  the  bulb  on  / 
becomes  hot ;  draw  about  1800  c.c.  of  air  through  the 
apparatus,  by  means  of  an  aspirator  connected  with  I, 
then  immediately  separate  a  from  /,  and  weigh  ^  and  hh' 
again  when  they  have  become  cold.  The  increase  in 
weight  gives  the  carbonic  anhydride. 

The  tube  ^  can  be  used  several  times  if  it  is  carefully 
closed  when  not  in  use.  If  the  tube  hh'  is  used  a  second 
time,  it  will  be  safer  to  connect  another  with  it  on  the 
outside,  filled  in  the  same  way ;  if  this  second  tube  does 
not  gain  in  weight,  the  first  one  may  be  used  a  third  time, 
with  the  same  j^recaution ;  if  it  does  gain  notably,  use  it 
alone  in  the  third  analysis,  and  re-fill  A  A'. 

c.  It  often  happens  that  carbonic  acid  and  chlorine  are 
to  be  estimated  in  the  same  substance ;  in  this  case,  after 
making  the  determination  of  the  acid  by  either  of  the 
above  methods,  using,  of  course,  pure  nitric  acid  to  set  it 
free,  filter  the  contents  of  the  flask  if  not  perfectly  clear, 
and  precipitate  the  chlorine  in  the  filtrate  and  washings 
with  argentic  nitrate. 

PHOSPHORIC  ACID.     H3PO4.    98. 

61  •  All  phosphates  except  those  of  the  alkaline  metals 
are  insoluble  in  water,  but  all  are  soluble  in  acids. 

Reactions. — When  a  solution  of  a  phosphate  is  added 
to  one  of  magnesia  containing  an  ammoniacal  salt  and 
an  excess  of  ammonia,  a  white  flocculent  precipitate, 
MgNH^PO^,  is  produced,  which,  after  standing  for  a 
time  in  a  warm  place,  becomes  more  granular  and  crys- 
talline ;  in  very  dilute  solutions  the  precipitate  does  not 
appear  until  after  long  standing,  and  is  then  crystalline, 
and  adheres  to  the  sides  of  the  tube  in  the  same  manner 
as  described  under  magnesium. 


84  §    61.       BASES    AND    ACIDS    WITH    KEAGENTS. 

When  a  very  small  quantity  of  a  solution  of  a  phos- 
phate is  added  to  a  considerable  quantity  of  a  solution  of 
amnionic  molybdate,  containing  an  excess  of  nitric  acid, 
a  lemon-yellow,  pulverulent  precipitate  is  formed,  at  once 
or  after  long  standing ;  a  portion  of  the  precipitate  ad- 
heres strongly  to  the  sides  of  the  tube.  This  precipitate 
is  soluble  in  a  solution  of  a  phosphate  and  in  ammonia, 
but  is  insoluble  in  dilute  nitric  acid  in  the  presence  of 
excess  of  the  molybdate.  The  reaction  is  exceedingly 
delicate. 

Quantitative  estimation. — a.  In  cases  where  the  acid 
is  free  or  combined  with  an  alkaline  metal  only,  the  deter- 
mination of  it  may  be  made  as  magnesic  phosphate. 
Mo-  P  O  . 

■^-^&2-^    2^7* 

Neutralize  a  quantity  of  the  solution  of  the  substance 
containing  not  more  than  0.2  grm.  of  the  acid  with  am- 
monia, if  it  is  acid,  and  add  magnesia  mixture  {§  18,  h) 
as  long  as  a  precipitate  is  formed ;  12-15  c.c.  of  the  re- 
agent will  be  required  for  0.2  grm.  of  ^fi,^ ;  then  add 
diluted  amnionic  hydrate  containing  one  part  of  ammonia- 
water  of  0.96  Sp.  Gr.  and  "three  of  water,  until  the  vol- 
ume of  the  mixture  is  about  110  c.c,  and  proceed  further 
as  directed  for  the  treatment  of  the  same  precipitate  un- 
der magnesium  (§50,  a).  It  contains  63.96°  |„  of  phos- 
phoric anhydride,  PjOj.. 

If  in  any  case  the  precipitate  has  a  somewhat  suspi- 
cious flocculent  appearance,  and  does  not  become  crystal- 
line after  long  digestion,  it  had  better  be  dissolved  in 
dilute  hydrochloric  acid  on  the  filter ;  evaporate  the  solu- 
tion to  dryness  on  the  water-bath,  treat  the  residue  with 
dilute  hydrochloric  acid,  and  precipitate  the  phosphoric 
acid  again  with  magnesia  mixture  as  before.  Kevcrthe- 
less  it  is  best  to  avoid  the  necessity  of  this  re-solution  and 
re-precipitation  if  possible,  by  careful  attention  to  the  di- 
rections for  removing  silicic  acid  and  other  substances 
from  the  solution  at  the  proper  time  and  in  the  proper 


§  61.     PHOSPHORIC  ACID.  85 

place  ;  according  to  Kubel  (  Versuchs  Stationen,  10,  123) 
there  is  a  lo3s  of  magnesia  when  the  i)recipitated  plios- 
phate  is  dissolved  and  re-precipitated. 

b.  In  the  presence  of  alkaline  earths,  alumina,  ferric 
oxide,  and  manganous  oxide,  phosphoric  acid  is  best  de- 
termined indirectly,  by  precipitation  as  ammoulc phospho- 
molyhdate.  If  silica  is  present,  it  must  first  be  removed 
by  evaporation  to  dryness  in  the  usual  manner  (§  58,  «,  1). 

.  To  the  solution,  free  from  silicic  acid,  add  the  solution 
of  ammonic  molybdate  containing  an  excess  of  nitric 
acid,  whose  preparation  is  described  in  §  3,  /,  and 
which,  if  made  as  there  directed,  contains  5''|o  of  molyb- 
dic  acid,  in  sucli  a  quantity  that  the  amount  of  molybdic 
acid  added  shall  be  from  40  to  60  times  as  great  as  that 
of  the  phosphoric  acid  supposed  to  be  in  the  solution  ; 
since  the  molybdic  acid  must  be  so  largely  in  excess,  it  is 
well  to  take  a  quantity  of  the  solution  of  phosphate  that 
contains  not  over  0.1  grm.  of  the  acid,  and  the  solution 
sliould  be  tolerably  concentrated.  Digest  the  mixture 
from  12  to  24  hours  at  a  temperature  of  about  40°  C. ;  then 
take  out  a  small  sample  of  the  clear  liquid  with  a  pipette, 
mix  it  in  a  test-tube  with  its  volume  of  ammonic  molyb- 
date, and  heat  the  mixture  gently  for  an  hour  or  more. 
If  more  of  the  precipitate  appears,  rinse  the  test-tube  into 
the  beaker  again,  add  more  ammonic  molybdate,  digest 
12  hours  longer,  and  repeat  the  test.  Not  until  the  mix- 
ture remains  perfectly  clear  in  this  test  may  the  precipita- 
tion be  considered  as  finished. 

Collect  the  precipitate  on  a  small  filter,  rinse  the  beaker 
out  with  portions  of  the  filtrate,  and  wash  the  contents 
of  the  filter  with  a  mixture  of  100  parts  of  the  solution  of 
ammonic  molybdate,  20  parts  of  nitric  acid  (Sp.  Gr.  =  1.2), 
and  80  parts  of  water  {i^es.  Zeitschrift  6,  405),  until,  in 
case  lime  was  present,  the  filtrate  gives  no  turbidity  in 
strong  alcohol  to  which  sulphuric  acid  has  been  added. 
Dissolve  the  precipitate  in  the  smallest  quantity  of  am- 


86  61.       BASES    AXD    ACIDS    WITH    REAGENTS. 

monia  (Sp.  Gr.  =  0.96),  wash  out  tlie  filter  wiih  a  mix- 
ture of  3  parts  of  water  and  1  of  ammonin,  and  wash  off 
what  remains  adhering  to  the  walls  of  the  beaker,  in 
Avhich  the  phospho-molybdate  Avas  precipitated,  with  a 
little  of  the  same  ammonia  water,  or  else  collect  this  so- 
lution of  the  whole  precipitate  in  that  beaker ;  add  di- 
lute hydrochloric  acid  to  the  strong  ammoniacal  solution, 
until  the  yellow  precipitate,  that  appears  with  each  drop 
of  the  acid  added,  begins  to  dissolve  again  with  some  dif- 
ficulty, showing  that  the  ammonia  is  nearly  neutralized, 
then  add  the  magnesia  mixture  as  long  as  a  precipitate  is 
produced,  and  the  proper  amount  of  the  diluted  ammonia, 
and  proceed  as  in  a. 

LatschinoAV  (Fres.  Zeitschrift  7,  215)  asserts  that  this 
precipitate  of  ammonio-raagnesic  phosphate  must  be  fused 
with  potassic  sodic  carbonate,  the  fused  mass  extracted 
Avith  water,  and  this  solution  precipitated  again  with  the 
magnesia  mixture  in  the  usual  manner,  after  addition  of  a 
little  citric  acid. 

c.  In  the  absence  of  at  least  all  but  small  quantities  of 
iron  and  aluminium,  phosphoric  acid  may  be  determined 
with  sufiicient  accuracy  for  industrial  purposes  by  a  volu- 
metric method,  that  depends  upon  the  following  reactions. 
First,  when  a  solution  of  uranic  salt  is  added  to  one  of  a 
phosphate  containing  no  other  free  acid  than  acetic,  the 
uranic  oxide  is  immediately  precipitated  in  combination 
with  phosphoric  acid.  Second,  a  solution  containing  the 
least  traces  of  uranic  oxide  gives  a  brown  precipitate  with 
potassic  ferrocyanide. 

Preparation  of  the  standard  sohitlo7is. 

1.  Dissolve  12.6056  grms.  of  pure  crystallized  hydric 
disodic  phosphate,  that  does  not  show  the  least  signs  of 
efilorescence,  and  lias  been  thoroughly  dried  in  powder 
by  pressure  between  folds  of  bibulous  paper,  in  about  300 
c.c.  of  water,  and,  when  the  temperature  of  the  solution 
is  15°  C,  make  the  volume  up  to  exactly  500  c.c.  with  dis- 


61.       PHOSPHORIC    ACID.  87 

tilled  water.     One  cubic  centimetre  of  such  a  solution  con- 
tains 0.005  grni.  of  phosphoric  anhydride,  P20^. 

2.  Dissolve  100  grms.  of  sodic  acetate  in  900  c.c.  of 
water,  and  add  100  c.c.  of  concentrated  acetic  acid. 

3.  Dissolve  about  33  grms.  of  uranic  acetate  in  about 
1  litre  of  water,  and  j^roceed  to  titrate  this  solution  witli 
reference  to  the  standard  solution  of  phosphate  so  that  1 
cubic  centimetre  of  it  shall  exactly  precipitate  0.005  grm. 
of  phosphoric  anhydride,  as  follows. 

Put  25  c.c.  of  the  standard  phosphatic  solution  in  a 
small  flask,  add  5  c.c.  of  the  solution  of  sodic  acetate, 
heat  to  about  50°  C,  add  5  or  10  c.c.  of  the  uranic  solution 
from  a  burette  or  graduated  pipette,  heat  to  boiling,  and 
let  the  mixture  stand  a  few  minutes  ;  the  precipitate  wi.l 
settle  quickly,  and  a  drop  of  the  clear  supernatant  liquid 
can  be  taken  out  on  the  end  of  a  small  glass  rod,  and 
tested  with  the  solution  of  potassic  ferrocyanide  for  ex- 
cess of  uranic  oxide ;  this  test  is  best  made  by  letting  the 
drop  fall  gently  in  the  middle  of  a  small  shallow  pool  of 
the  solution  of  ferrocyanide,  on  a  white  porcelain  plate, 
when  the  slightest  excess  of  the  uranic  oxide  in  the  solu- 
tion will  be  manifested  by  the  formation  of  a  brown  zone 
where  the  two  liquids  come  in  contact;  the  color  soon 
spreads  throughout  the  entire  liquid.  If  no  color  appears, 
add  5  c.c.  more  of  the  uranic  solution,  boil  again,  let  set- 
tle, and  test  a  drop  of  the  supernatant  liquid  in  another 
little  pool  of  the  ferrocyanide,  and  so  proceed  until  a 
brown  color  is  produced  in  the  test  drop.  Suppose  that 
this  brown  color  was  obtained  after  adding  20  c.c.  of  the 
uranic  solution,  but  not  after  adding  15 ;  repeat  the  trial 
now  with  a  fresh  quantity  of  the  standard  phosphatic  so- 
lution, adding  16  c.c.  of  the  uranic  solution  at  once,  be- 
fore making  the  test,  and  repeating  the  test  after  each 
addition  of  a  cubic  centimetre  at  a  time.  If,  in  this  trial, 
we  find  that  a  brown  color  is  obtained  with  IT  c.c.  but 
not  with  16,  we  may  make  a  third  trial  with  another  por- 


88  62.       BASES    AXD    ACIDS    WITH  *IlEAGE>sTS. 

tion  of  the  standard  pliosphatic  solution,  and  locate  the 
point  of  saturation  more  accurately  between  16  and  17 
cubic  centimetres,  beginning  with  16.1  c.c.  and  so  on. 

If  we  find,  finally,  that  25  c.c.  of  the  standard  phos- 
phatic  solution  requh-es  16.5  c.c.  of  the  uranic  solution  for 
the  complete  precipitation  of  the  phosphoric  acid,  then, 
evidently,  to  every  16.5  c.c.  of  the  former,  8.5  c.c.  of  pure 
water  must  be  added,  in  order  to  make  a  standard  uranic 
solution,  each  cubic  centimetre  of  which  shall  be  exactly 
equivalent  to  0.005  grm.  of  phosphoric  anhydride. 

The  respective  quantities  of  uranic  solution  and  wa>er 
being  carefully  measured  out  and  mixed,  for  making  half 
a  litre  or  a  litre  of  the  standard  solution,  this  solution 
should  be  tested,  in  order  to  be  sure  of  its  value  with 
respect  to  phosphoric  acid.  Dilute  5  c.c.  of  the  standarl 
phosphatic  solution,  add  1-2  c.c.  of  sodic  acetate,  and 
then  add  the  uranic  solution  from  a  burette  graduated  into 
^  Ijq  cubic  centimetres  ;  exactly  5  c.c,  not  a  tenth  more  or 
less,  should  be  required  before  the  reaction  with  the  ferro- 
cyanide  is  given. 

The  method  of  determining  phosphoric  acid  volumet- 
rically,  with  the  aid  of  this  standard  uranic  solution,  is 
the  same  as  that  just  described  for  the  determination  of 
the  strength  of  this  solution  as  originally  prepared.  The 
amount  of  phosphoric  anhydride  in  the  quantity  of  the 
solution  taken  is  then  given,  by  the  product  of  0.005 
into  the  number  of  cubic  centimetres  of  standard  uranic 
solution  required  to  precipitate  the  acid. 

NITRIC  ACID.     IINO3.     68. 

62.  All  nitrates  are  soluble  in  water. 

Reactions. — If  a  nitrate  is  heated  with  concentrated 
sulphuric  acid  and  copper  turnings,  red  fumes  of  nitric 
peroxide,  NO3,  become  visible  in  the  upper  part  of  the 


62.       NITKIO    ACID.  89 

tube,  particularly  if  it  is  held  over  white  paper  and  looked 
through  lengthwise. 

If  a  nitrate  is  mixed  in  a  test-tube  with  strong  sul- 
phuric acid  and  the  mixture  is  allowed  to  cool,  and  a  con- 
centrated solution  of  ammonio-ferrous  sulphate  is  then 
poured  slowly  down  the  sides  of  the  tube  so  as  to  float 
on  the  surface  of  the  liquid  in  it,  a  colored  ring  is  formed, 
the  tint  of  which  may  range  from  a  rose  color  to  a  dark 
brown,  according  as  little  or  much  nitric  acid  is  present. 

If  a  solution  of  a  nitrate  is  poured  into  a  test-tube  con- 
taining 2-3  grms.  of  a  mixture  of  clean  iron  filings  and 
granulated  zinc,  or  of  sodium  amalgam,  and  5-6  c.c.  of  a 
strong  solution  of  potash  or  soda  are  added,  and  the  mix- 
ture is  heated  to  boiling,  ammonia  is  set  free  ;  its  presence 
in  the  tube  may  be  detected  by  moistened  turmeric-paper, 
or  by  holding  in  the  tube 'a  drop  of  Nessler's  solution, 
suspended  on  the  end  of  a  glass  rod ;  this  solution  will  be 
colored  reddish-brown. 

A  delicate  test  for  nitric  acid  in  rain-water  consists  in 
acidifying  100  c.c.  of  the  water  with  2  or  3  drops  of  con- 
centrated sulplmric  acid,  adding  2  or  3  pieces  of  pure 
zinc,  and,  immediately,  a  freshly  prepared  mixture  of 
jiotassic  iodide  with  a  little  boiled  starch  paste  ;  the  pres- 
ence of  nitric  acid  is  indicated  by  a  blue  color.  The  re- 
agents used  should  be  tested  by  mixing  them  together 
without  the  water. 

If  the  water  contained  nitrous  acid^  it  will  give  a  blue 
color  with  potassic  iodide  and  starch  paste  alone. 

Quantitatiye  estimation.— a.  Of  the  numerous  meth- 
ods of  determining  nitric  acid,  that  of  Schlossing  has 
proved  the  most  satisftictory  in  all  cases.  Friihling  and 
Grouven  have  simplified  Schlossing's  apparatus  somewhat. 
{Die  landwirthschaftlichen  Yersuchs-Stationen^  9,  13.) 

The  dissolved  nitrate  is  introduced  into  the  flask  A,  of 
about  400  c.c.  capacity,  whose  mouth  can  be  perfectly 
closed  by  a  rubber  cork,  through  which   passes  a  glass 


90 


62. 


BASES    AND    ACIDS    WITH    REAGENTS. 


tube,  a  ;  the  rubber 


tube  ho  should  be  about  8  cm.  long, 


and  have  a  clamp  on  it ;  d  is  another  narrow  caoutchouc 
tube,  15  cm.  long.  The  neck  of  the  jar  B  is  ground  on 
the  outside  so  that  a  rubber  tube  slipped  over  it  will 
more  readily  make  a  tight  joint ;  a  small  glass  tube,  g^ 
is  connected  with  the  jar  by  the  stop-cock  h  and  rubber 
tubing ;  another  glass  tube,  /,  bent  at  an  obtuse  angle,  and 
reaching  above  the  level  of  the  stop-cock  ^,  is  fastened  in 
the  tubulure  m  of  the  jar  by  a  good  cork.  TJiis  last- 
mentioned  tube  being  in  place,  open  the  stop-cock  h^  pour 

a  little  boiled 
water  into  the  jar 
through  the  tube 
/,  and  then  pour 
in  mercury  until 
it  rises  to  the 
lower  rim  of  the 
rubber  tube  f  on 
the  neck  of  the 
jar ;  close  the 
stop-cock,  put  the 
jar  in  the  mercury 
troutrh  so  that 
the  mercury  rises 
above  the  tubulure,  and  remove  the  glass  tube  I  and 
the  cork ;  now,  by  means  of  a  pipette,  the  lower  end  of 
which  is  bent  so  that  it  can  be  inserted  in  the  tubulure, 
introduce  50  c.c.  of  well-boiled  rriilk  of  hme,  and  then 
cover  the  mercury  in  the  trough  with  water  to  the  depth 
of  about  3  cm. 

The  solution  of  the  nitrate  in  A,  which  must  be  neutral 
or  alkaline,  is  boiled  down  to  a  small  volume,  while  the 
open  end  of  d  is  immersed  in  water ;  when  the  bubbles  of 
gas  escaping  from  A  are  completely  condensed  in  passing 
through  the  water,  showing  that  all  the  air  has  been  ex- 
pelled from  the  liquid  in  A,  close  the  clamp  on  5c,  and 


§    62.-     NITEIC    ACID.  91 

dip  d  m  a  glass  containing  a  solution  of  ferrous  chloride 
in  hydrocliloii.^  acid,  remove  the  lamp  from  A,  and  open 
the  clamp  just  enough  to  allow  this  solution  to  flow  into 
the  flask  rather  rapidly;  when  about  200  c.c.  of  the  fer- 
rous solution  have  passed  in,  replace  this  solution  by  dilute 
hydrochloric  acid,  and  allow  three  or  four  portions  of  this 
to  flow  in  also,  and  thus  wash  all  the  ferrous  salt  out  of  the 
tube ;  finally  rinse  the  tube  into  the  flask  with  a  little  dis- 
tilled water.  Now,  close  the  clamp  on  be,  and,  without 
allowing  any  air  to  enter  the  tube,  insert  d  in  the  tubulure 
of  the  jar  B,  replace  the  lamp  under  A,  immediately  open 
the  clamp>  on  be,  while  holding  the  rubber  tube  tightly 
compressed  between  the  fingers  until  a  pressure  is  felt 
from  within ;  then  remove  the  fingers  and  allow  the  nitric 
oxide  gas  that  is  generated  in  the  flask  to  pass  into  the 
receiver  B.  The  reaction  is  generally  tenninated  in  about 
8  minutes ;  so  long  as  nitric  oxide  is  escaping  it  bubbles 
up  through  the  milk  of  lime  in  B,  but  as  soon  as  nothing 
but  water  and  hydrochloric  acid  pass  over,  both  are 
absorbed  by  the  milk  of  lime,  and  the  bubbling  of  the  gas 
through  it  ceases. 

If  the  receiver  B  is  filled  with  gas  before  all .  the  nitric 
acid  in  A  is  decomposed,  close  the  clamp  on  be,  remove 
the  lamp  immediately  from  under  A,  take  the  rubber  tube 
d  out  of  the  tubulure  and  let  it  lie  in  the  water  over  the 
mercury,  while  the  receiver  is  emptied  in  the  manner  de- 
scribed below ;  then  fill  the  receiver  again  with  mercury 
and  milk  of  lime  as  directed  above,  insert  d  in  the  tubu- 
lure again,  apply  heat  to  A  while  the  tube  bo  is  closed 
■with  the  fingers  only,  and  proceed  as  before,  until  the  de- 
composition of  the  nitric  acid  is  finished. 

When  the  evolution  of  gas  finally  ceases,  close  be,  re- 
move d  from  the  tubulure,  and  proceed  to  empty  the  gas 
from  B.  To  this  end,  mount  another  flask,  C,  in  the  same 
manner  as  A  was  arranged,  put  about  100  c.c.  of  distilled 
water  in  it,  attach  a  rubber  tube  about  12  cm.  long  to  the 


92  62.       BASES    AND    ACIDS    WITH    REAGENTS. 

glass  tube  that  passes  through  the  well-fitting  rubber  cork 
in  the  mouth  of  the  flask,  and  put  a  clamp,  y,  on  the  end 
of  the  tube.  Fasten  this  clamp  open  and  boil  the  water 
in  C  until  the  air  is  completely  expelled  from  the  flask, 
and,  while  steam  is  still  escaj^ing  from  the  end  of  the  rub- 
ber tube,  slip  it  over  the  glass  tube  </  on  the  receiver,  and 
at  the  same  moment  open  the  stop-cock  h  ;  the  aqueous 
vapor,  from  the  Avater  that  continues  to  boil  in  the  flask, 
condenses  at  first  in  the  neck  of  the  receiver  and  washes 
the  milk  of  lime  out  of  the  upper  part  of  it  and  out  of 
the  glass  tube ;  if  any  milk  of  lime  is  carried  into  C  in' 
the  operation  that  follows,  the  analysis  is  worthless. 

Now,  remove  the  lamp  from  C,  and  a  current  starts  in 
the  opposite  direction,  which  carries  the  nitric  oxide  into 
C ;  the  rapidity  of  the  flow  can  be  regulated  by  compress- 
ing the  rubber  tube  between  the  fingers  ;  as  soon  as  the 
milk  of  lime  in  the  receiver  has  reached  the  rim  of  the 
rubber  tube/,  close  the  stop-cock  Ti,  and  conduct  20  or  30 
c.c.  of  pure  hydrogen  into  the  receiver,  oj^en  the  stop-cock 
and  allow  this  gas  to  flow  into  C  ;  repeat  this  two  or  three 
times,  thus  carrying  the  last  traces  of  nitric  oxide  from 
B  to  C.  Now,  close  h  again  and  also  the  clamp  y  near 
this  end  of  the  tube,  connect  the  rubber  tube  Avith  a 
small  gasometer  containing  oxygen,  open  the  cOck  of  the 
gasometer  and  the  clamp  y  again,  and  oxygen  will  pass 
into  C  and  convert  the  nitric  oxide  into  nitric  acid ;  when 
all  the  oxygen  has  passed  into  the  flask  that  will,  close 
the  gasometer  cock,  disconnect  the  rubber  tube  from  it, 
and,  after  about  15  minutes,  determine  the  nitric  acid  in 
the  liquid  in  C  by  means  of  the  '1^^  standard  solution  of 
soda ;  each  cubic  centimetre  of  the  sodic  solution,  con- 
taining ^Ijp  of  an  equivalent  of  sodic  oxide  (Na^O),  will 
combine  with  '1^^  of  an  equivalent  of  nitric  anhydride 
N^Oj^,  expressed  in  milligrammes  =  5.4  mgr.  or  0.0054  grm. 

h.  Nitric  acid  may  be  very  conveniently  estimated  in 
nitrates,  as,  for  example,  when  it  is  desired  to  test  the 


§    62.      NITKIC   ACID.  93 

purity  of  nitre  or  of  Chili  saltpetre,  by  its  expulsion  at  a 
high  temperature  by  another  acid,  as  silicic  or  chromic, 
that  is  not  volatile  at  such  a  temperature. 

Fuse  a  quantity  of  the  salt,  free  from  carbonic  acid, 
ammonic  salts,  or  organic  matter,  at  the  lowest  possible 
temperature,  pour  it  on  a  warm  porcelain  plate,  pulverize 
the  cake,  and  dry  the  powder  thoroughly  ,•  then  put  2-3 
grms.  of  finely  powdered  quartz  in  a  platinum  crucible, 
and  ignite  it  strongly;  add  to  this  about  0.5  grra.,  care- 
fully weighed,  of  the  nitrate  prepared  as  above  directed, 
mix  the  two  substances  carefully  with  a  dry  glass  rod, 
wipe  oif  the  rod  with  a  little  more  of  the  quartz  powder, 
and  weigh  the  whole ;  ignite  the  well-covered  crucible 
with  its  contents,  for  half  an  hour,  at  a  barely  visible  red 
heat,  weigh,  and  count  the  loss  as  nitric  anhydride.  Sul- 
phates or  chlorides  are  not  decomposed  under  these  cir- 
cumstances, but,  if  carbonates  are  present,  they  must  be 
removed  by  previous  treatment  of  the  salt  with  hydro- 
chloric acid  in  slightest  possible  excess,  and  evaporation 
to  dryness  on  the  water-bath. 

c.  A  very  convenient  method  for  determining  nitric 
acid  in  nitrates  is  given  by  C.  Noellner.  (Fres.  Zeitschrift 
6,  375),  It  depends  npon  the  solubility  of  ammonic  nitrate 
in  absolute  alcohol,  and  the  insolubility  of  other  salts  of 
the  alkalies  and  alkaline  earths. 

Heat  a  quantity  of  the  salt  containing  not  more  than 
0.2  grm.  of  the  nitre  with  a  small  quantity  of  a  solution  of 
ammonic  sulphate  ;  ammonic  nitrate  is  formed,  and  this 
remains  in  solution  while  all  other  salts  are  precipitated, 
when  absolute  alcohol  is  added  to  the  liquid ;  let  the  mix- 
ture stand  a  few  minutes,  filter  it,  wash  the  precipitate, 
add  an  alcoholic  solution  of  potassa  to  the  filtrate,  collect 
the  precipitated  potassic  nitrate  on  a  dried  and  weighed 
filter,  wash  it  with  alcohol,  dry  it  at  100°,  and  weigh  it. 


94  63.       BASES    AND    ACIDS    WITH    REAGENTS. 

HYDROCHLORIC  ACID.    IICl.     36.5. 

63.  Chlorides  of  all  the  metals  in  the  list  in  §  43  are 
soluble  in  water.  Plumbic  chloride  is  sparingly  soluble 
in  cold  water  but  readily  soluble  in  hot. 

Reaction. — When  argentic  nitrate  is  added  to  a  solu- 
tion containing  a  chloride  or  hydrochloric  acid,  a  white 
precipitate  is  produced,  AgCl,  which,  if  at  all  abundant, 
is  collected  together  in  curdy  flakes  on  violently  agitating 
the  mixture.  This  precipitate  is  blackened  on  exposure 
to  the  light,  is  insoluble  in  dilute  nitric  acid,  but  is  solu- 
ble in  ammonia ;  from  this  solution  it  is  re-precipitated 
unchanged,  on  addition  of  nitric  acid  in  excess.  It  can 
be  fused  without  decomposition.  In  contact  Avith  metal- 
lic zinc  in  the  presence  of  sulphuric  acid,  it  is  decomposed, 
metallic  silver  being  set  free. 

Quantitative  estimation. — Hydrochloric  acid  or  chlo- 
rine is  most  easily  and  accurately  determined  by  precipi- 
tation as  argentic  chloride,  and  the  estimation  may  be 
made  either  by  a  gravimetric  or  a  volumetric  process. 

a.  Gravimetric  Process. — Add  the  solution  of  argentic 
nitrate,  containing  a  slight  excess  of  nitric  acid,  to  the  so- 
lution of  the  chloride,  heat  the  mixture  and  stir  or  shake 
it  vigorously  to  cause  the  precii^itate  to  settle  more  read- 
ily, let  it  stand  until  the  supernatant  liquid  is  quite  clear, 
decant  the  liquid  through  a  small  filter,  agitate  the  pre- 
cipitate with  hot  water,  transfer  it  to  the  filter  with  the 
aid  of  a  little  water  acidulated  with  nitric  acid,  wash  it 
at  first  with  the  same  acidulated  water  and  afterwards 
with  pure  water,  until  the  washings  give  no  turbidity 
with  ammonic  chloride. 

Dry  the  filter  and  its  contents,  separate  the  latter  from 
the  filter  as  completely  as  possible,  burn  the  filter  on  the 
crucible  cover,  add  the  ash  to  the  precipitate  in  the  cruci- 
ble, heat  the  whole  some  time  with  a  little  nitric  acid,  add 
a  little  hydrochloric,  evaporate  carefully  to  dryness  on  the 


63.      HYDEOCHLOEIC   ACID.  95 

water-bath,  ignite  the  residue  until  it  begins  to  fuse,  and 
weigh  it. 

When  this  precipitate  of  argentic  chloride  is  produced 
in  the  presence  of  much  organic  matter,  it,  together  with 
the  ash  of  the  filter,  must  be  fused  with  3  or  4  parts  of 
pure  sodic  carbonate,  and  the  fused  mass  exhausted  with 
w^ater,  the  insoluble  residue  w^ell  washed,  and  the  solu- 
tions and  washings  re-precipitated  with  argentic  nitrate, 
and  the  precipitate  treated  as  directed  above  for  washing 
and  ignition. 

The  precipitate  contains  24.74"  \^  of  chlorine. 

b.  Volumetric  Process. — To  prepare  the  standard  solu- 
tion of  argentic  nitrate,  dissolve  18.75-18.8  grms.  of 
the  pure  fused  salt  in  1100  c.c.  of  distilled  water,  filter 
the  solution  if  necessary,  and  mix  all  parts  of  it  well 
together. 

Weigh  out  accurately  four  portions  of  pure  sodic  chloride 
of  0.1-0.18  grms.  each;  the  salt  should  have  been  pre- 
viously gently  ignited,  pulverized  while  warm,  and  kept 
in  a  well  stoppered  bottle  until  wanted  for  use. 

Dissolve  each  portion  of  the  salt  in  20-30  c.c.  of 
water,  and  add  2  or  3  drops  of  a  cold  saturated  solution 
of  potassic  chromate.  Now,  allow  the  solution  of  argen- 
tic nitrate  to  flow  from  a  burette,  graduated  into  ^1^^  c.c, 
into  one  of  these  solutions,  slowly  and  with  constant  stir- 
ring ;  each  drop  as  it  comes  in  contact  w^ith  the  liquid 
produces  a  red  precipitate,  which,  at  first,  disappears  when 
mixed  with  the.  rest  of  the  solution,  but  finally  the  addi- 
tion of  a  single  drop  causes  the  red  color  to  remain  per- 
manent ;  all  the  chlorine  has  united  with  the  silver. 

A  solution  of  argentic  nitrate  is  to  be  made,  one  litre 
of  which  will  exactly  precipitate  the  chlorine  in  'L  of 
an  equivalent  of  sodic  chloride  expressed  in  grammes,  or 
5.85  grms.  If  the  amount  of  sodic  chloride  in  the  solu- 
tion tested  in  this  first  experiment  was  0.11  grm.,  and 


96  63.       BASES    AND    ACIDS    WITH    REAGENTS. 

18.7  c.c.  of  argentic  nitrate  were  required,  we  learn  by 
the  proportion, 

0.11  :  18.7  =  5.85  :  994.5, 

how  much  of  the  argentic  solution  that  we  liave  made 
would  be  required  for  the  desired  purpose;  we  must 
therefore  add  5.5  c.c.  of  distilled  water  to  994.5  c.c.  of  the 
argentic  solution,  to  make  a  litre  of  a  solution  that  shall 
be  exactly  equivalent  to  5.85  grms.  of  sodic  chloride,  or 
3.55  grms.  of  chlorine ;  or,  since  it  is  more  convenient  to 
measure  out  one  litre  of  the  solution,  and  add  a  small 
quantity  of  water  accurately  measured  with  the  pipette, 
we  may  learn  from  the  projoortion, 

994.5  :  4.5  =  1000  :  x, 
how  much  water  will  be  required  for  one  litre. 

Repeat  the  test  made  with  one  jDortion  of  the  salt  with 
two  of  the  remaining  three  portions,  keeping  the  first  at 
hand  as  a  standard  of  com23arison,  substitute  the  mean  of 
the  quantities  of  salt  taken  and  of  the  three  correspond- 
ing results  in  the  place  of  the  first  and  second  terms  in 
the  first  proportion  given  above,  and  make  the  standard 
silver  solution  accordingly;  then,  in  order  to  be  sure  that 
the  work  has  been  correctly  done,  rinse  the  burette  out 
with  a  little  of  the  solution  last  prepared,  fill  up  to  the 
zero  mark  with  this  solution,  and  make  a  fourth  trial  with 
the  last  weighed  j)ortion  of  the  sodic  chloride.  The  num- 
ber of  cubic  centimetres  of  the  standard  solution  required, 
multiplied  by  0.00585,  should  give  a  product  exactly  equal 
to  the  amount  of  salt  taken. 

One  cubic  centimetre  of  this  solution  corresponds  to 
0.00355  grm.  of  chlorine. 

The  solution  in  which  chlorine  is  to  be  determined 
with  the  aid  of  this  standard  solution  must  not  be  acid 
in  the  slightest  degree,  but  should  be  neutral,  or  at  the 
most  very  slightly  alkaline.  If  strongly  alkaline,  it  should 
first  be  neutralized  with  nitric  acid ;  if  acid,  with  sodic 


§    64.       HYDROCYANIC    ACID.  97 

carbonate.  Of  course,  neither  of  these  reagents  should 
contain  any  chlorine.  Greater  accuracy  is  secured,  more- 
over, by  using  the  same  volume  of  a  solution  containing 
about  the  same  amount  of  chlorine  as  in  determining  the 
standard  of  the  argentic  solution  in  the  beginning — that 
is,  about  25  c.c.  containing  about  0.15  grm.  of  chlorine. 

It  is  well,  also,  to  have  on  hand  an  accurately  titrated 
solution  of  sodic  chloride,  containing  exactly  5.85  grms. 
of  sodic  chloride  in  the  litre,  and  which,  therefore,  is  ex- 
actly equivalent,  cubic  centimetre  for  cubic  centimetre,  to 
the  argentic  solution.  Then,  if  it  is  feared  in  any  case 
that  too  much  argentic  nitrate  has  been  added,  a  cubic 
centimetre  of  this  solution  can  be  put  in,  when  the  red 
coloration  will  disappear,  and  argentic  nitrate  can  be  add- 
ed again  more  cautiously ;  finally,  when  the  desired  result 
is  obtained,  subtract  one  from  the  number  of  cubic  centi- 
metres of  argentic  solution  used. 

HYDROCYANIC  ACID     HCy. 

64.  Cyanides  of  manganese,  zinc,  and  copper,  are  in- 
soluble in  water. 

Reactions* — Cyanides  give  a  white  precipitate,  AgCy, 
with  argentic  nitrate,  insoluble  in  dilute  nitric  acid,  and 
somewhat  difficultly  soluble  in  ammonia ;  when  heated, 
it  is  decomposed,  metallic  silver  being  left  behind. 

If  a  cyanide  is  treated  with  dilute  sulphuric  acid  in  a 
watch-glass,  and  another  watch-glass,  with  a  drop  of 
lammonic  sulphide  charged  with  excess  of  sulphur  in  its 
'centre,  is  quickly  inverted  over  the  first  glass,  the  hydro- 
cyanic acid  evolved  from  the  cyanide  is  absorbed  by  the 
ammonic  sulphide,  and  on  evaporating  the  drop  in  the 
upper  glass  to  dryness  at  a  very  gentle  heat,  ammonic 
sulphocyanate  is  left,  which,  if  moistened  with  a  drop  of 
ferric  chloride,  gives  a  deep  red  color. 
5 


98  65.       BASES   AND    ACIDS   WITH    REAGENTS. 

HTDROFERROCYANIC  ACID.     HCfy. 

65.  Ferrocyanides  of  iron,  zinc,  manganese,  lead,  and 
copper,  are  insoluble  in  water ;  ferrocyanides  of  iron  and 
copper  are  insoluble  in  dilute  acids. 

Reactions* — Ferrocyanides  give  a  deep  blue  precipitate 
of  Prussian  blue,  FegFe^Cy^g,  with  ferric  chloride,  which 
is  not  soluble  in  dilute  hydrochloric  acid,  but  is  decom- 
posed by  sodic  hydrate,  the  blue  color  being  changed  to 
red. 

HYDROSULPHUmC  ACID.    H^S. 

66.  Sulphurets  of  arsenic,  lead,  copper,  iron,  manga- 
nese, and  zinc,  are  insoluble  in  water ;  the  first  three  are 
insoluble  in  dilute  acids. 

Reactions. — Sulphurets  give  with  argentic  nitrate  a 
black  precipitate,  Ag^S,  insoluble  in  dilute  nitric  acid  and 
in  ammonia. 

When  sulphurets  are  treated  with  hydrochloric  or  sul- 
phuric acid,  sulphuretted  hydrogen,  H^S,  is  evolved  with 
efiervescence  ;  the  gas  may  be  recognized  by  its  disagree- 
able odor,  and  the  property  of  blackening  lead-paper. 

HTDRIODIC  ACID.    HI. 

67.  Plumbic  iodide  is  sparingly  soluble  in  cold  water, 
but  readily  soluble  in  hot ;  other  iodides  are  soluble. 

Reactions. — Iodides  give  a  yellow  precipitate,  Agl, 
with  argentic  nitrate,  which  is  very  sparingly  soluble  in 
ammonia  and  in  dilute  nitric  acid. 

If  enough  potassic  dichromate  is  added  to  a  solution 
of  an  iodide  to  give  it  a  pale  yellow  color,  and  then  a  lit- 
tle hydrochloric  acid,  iodine  is  set  free,  which,  if  it  is 
present  in  notable  quantity,  gives  the  solution  a  darker 


§  68.       HYDIIOFLUOEIC   ACID.       §  69.       OXALIC   ACID.      99 

color ;    a  drop  of  this  solution  on  starch  paper  colors  it 
blue ;  the  latter  reaction  is  very  delicate. 

HYDROFLUORIC  ACID.     HF. 

68.  Calcic  and  magnesic  fluorides  are  difficulty  soluble 
in  water  and  acids. 

Reactions* — When  a  fluoride  in  powder  is  moistened 
with  concentrated  sulphuric  acid,  in  a  leaden  or  platinum 
cup,  and  gently  heated,  hydrofluoric  acid  is  evolved ;  if 
the  cup  is  covered  with  a  piece  of  Bohemian  glass  that  is 
protected  with  a  coating  of  wax,  except  along  a  few  lines 
where  the  wax  has  been  removed  with  a  sharp  point,  the 
glass  will  be  corroded  on  these  lines,  in  a  few  hours  at 
the  most.  If  but  a  small  quantity  of  hydrofluoric  acid  is 
present,  the  marks  may  not  be  seen  until  all  the  wax  is 
carefully  cleaned  off  and  the  glass  is  breathed  upon. 

To  be  sure  that  these  faint  marks  are  produced  by 
traces  of  hydrofluoric  acid  in  the  substance,  wipe  the 
glass  off  carefully  with  water,  and  see  that  they  can  be 
developed  again  by  the  breath — and  be  sure,  also,  that  the 
sulphuric  acid  used  does  not  contain  traces  of  hydroflu- 
oric acid,  as  it  sometimes  does. 

If  a  silicate  is  present,  this  reaction  may  not  take  place ; 
in  this  case  mix  the  substance  with  strong  sulphuric  acid 
in  a  watch-glass,  heat  until  the  mass  is  dry,  and  wash  the 
residue  off  with  water.  If  fluorine  was  present,  the  glass 
will  be  found  to  be  corroded  where  it  came  in  contact 
with  the  substance. 

OXALIC  ACID.  H2C2O4.     90. 

69.  Oxalates  of  barium,  calcium,  magnesium,  iron, 
manganese,  zinc,  lead,  and  copper,  are  sparingly  soluble, 
or  insoluble,  in  water,  but  soluble  in  dilute  acid. 

Reactions. — Oxalates  are  decomposed,  but  not  black- 
ened when  heated. 


100  §    69.      BASES   AND    ACIDS   WITH   EEAGENTS. 

When  an  oxalate  is  heated  with  plumbic  binoxide  and 
concentrated^ sulphuric  acid,  a  brisk  effervescence  ensues, 
carbonic  acid  being  set  free ;  if  a  drop  of  lime-water,  on 
the  end  of  a  glass  rod,  is  held  in  the  tube  above  the 
liquid,  it  is  made  turbid  by  precipitation  of  calcic  car- 
bonate. 

A  solution  of  an  oxalate  in  which  no  free  acid  except 
acetic  is  present,  gives  a  fine  white  precipitate,  CaC^O^, 
with  calcic  sulphate,  insoluble  in  acetic  acid. 

Quantitative  estimation, — a.  Oxalic  acid  may  be  ac- 
curately determined  by  a  volumetric  process  with  potassic 
permanganate. 

First  make  a  ^|  j„  standard  solution  of  oxalic  acid,  by 
mixing  together  10  c.c.  of  the  standard  acid  already 
made  and  90  c.c.  of  distilled  water.  Put  50  c.c.  of  this 
new  standard  solution,  containing  0.315  grm.  of  the  acid, 
in  a  beaker,  add  about  100  c.c.  of  water  and  6  to  8  c.c.  of 
concentrated  sulphuric  acid,  and  heat  to  about  60°  C ; 
put  the  beaker  on  a  sheet  of  white  paper  and  add  the 
standard  solution  of  permanganate  with  constant  stirring, 
in  the  same  manner  as  directed  for  the  determination  of 
iron  (§  52).  When  the  reaction  is  completed,  make  another 
trial  with  the  other  50  c.c.  of  the  ^1^^  standard  acid. 

The  standard  of  the  permanganic  solution  with  refer- 
ence to  oxalic  acid  being  determined,  to  estimate  the  acid 
in  any  substance,  whether  free  or  combined,  the  substance 
must  be  freed  from  all  other  compounds  that  act  in  the 
same  manner  on  the  permanganate,  such  as  ferrous  oxide, 
or  organic  matter ;  dissolve  it  in  water  or  hydrochloric 
or  sulphuric  acid,  add  400  to  500  c.c.  of  water  for  every 
gramme  of  oxalic  acid  supposed  to  be  present,  and  6  to  8 
c.c.  of  concentrated  sulphuric  acid,  and  proceed  to  titrate 
with  the  permanganic  solution  in  the  usual  way.  Let 
m,  =  the  amount  of  permanganate  used  to  oxidize  0.315' 
grm.  of  crystallized  oxalic  acid,  or  0.18  grm.  of  oxalic  an- 
hydride, and  m'  the  amount  required  to  oxidize  the  acid 


§    70.      ACETIC   ACID.  101 

in  the  quantity  of  substance  taken.     Then  from  the  pro- 
portion, 

VYi  :  0.18  =  m^  :  X, 
we  may  learn  how  much  oxalic  anhydride,  C^Og,  was  con- 
tained in  the  substance  analyzed. 

h.  Oxalic  acid  may  be  estimated  in  any  substance  con- 
taining it  and  free  from  carbonic  acid,  by  converting  it 
into  carbonic  acid  with  the  aid  of  manganic  oxide  and 
concentrated  sulphuric  acid,  and  determining  this  car- 
bonic acid.  Weigh  the  substance  in  the  flask  A,  Fig.  1, 
§  60,  add  about  the  same  weight  of  manganic  oxide  free 
from  carbonic  acid,  fill  B  with  concentrated  sulphuric 
acid,  weigh  the  whole  apparatus,  and  proceed  further  as 
in  the  estimation  of  carbonic  acid  with  this  form  of  ap- 
paratus (§  60,  a).  Each  equivalent  of  oxalic  anhydride, 
C2O3,  yields  two  equivalents  of  carbonic  anhydride,  CO^. 

ACETIC  ACID.    HC2H3O2.     60. 

70 •  All  acetates  are  soluble  in  water. 

Reactions. — Acetates  are  blackened  when  quickly  heat- 
ed to  a  high  temperature,  carbon  being  set  free. 

If  a  neutral  acetate  is  mixed  with  a  solution  of  ferric 
chloride,  a  deep  red  liquid  is  produced ;  on  boiling  the 
mixture  a  red  precipitate  is  formed. 

If  an  acetate  is  heated  with  concentrated  sulphuric  acid 
and  alcohol  in  about  equal  volumes,  acetic  ether  is  disen- 
gaged, the  pleasant  aromatic  odor  of  which  is  best  distin- 
guished from  that  of  common  ether,  which  may  be 
formed  from  sulphuric  acid  and  alcohol  alone,  after  the 
liquid  has  become  quite  cold. 

Quantitative  estimation.— Free  acetic  acid  may  be  es- 
timated by  a  volumetric  process,  with  the  aid  of  the 
standard  sodic  solution. 

Since  neutral  sodic  acetate  has  a  slightly  alkaline  re- 
action, it  is  best  to  ascertain  first,  the  relation  between 


102  §    '^1.       BASES    AND    ACIDS    WITH    EE AGENTS. 

this  Standard  solution  and  one  of  acetic  acid  of  known 
strength.  For  this  purpose  add  a  measured  quantity  of 
the  standard  sulphuric  acid  to  a  solution  of  sodic  acetate, 
but  not  enough  to  decompose  the  whole  of  the  acetate. 
Each  cubic  centimetre  of  the  sulphuric  acid,  containing 
0.04  grm.,  will  set  free  an  equivalent  quantity  of  acetic 
anhydride,  =  0,051  grm.,  or  of  the  hydrated  acid,  0.06  grm. 

Knowing,  then,  how  much  acid  has  been  set  free,  we  can 
titrate  the  mixture  with  the  standard  sodic  solution,  and 
learn  how  much  acetic  acid  each  cubic  centimetre  of  the 
sodic  solution  will  neutralize. 

Merz  recommends  the  use  of  a  tincture  of  turmeric  as 
a  coloring  matter  that  is  not  affected  by  neutral  sodic  ace- 
tate ;  the  addition  of  a  single  drop  of  the  soda  solution  to 
a  solution  of  sodic  acetate  colored  yellow  by  this  tincture 
produces  a  brown  color,  while  a  drop  of  acetic  acid  re- 
stores the  yellow  color.  ( Wagner's  Jahresbericht,  13,  498.) 

TARTARIC  ACID.     Il2C4H40«.     150. 

71.  Tartrates  of  barium,  calcium,  zinc,  and  copper,  are 
difficultly  soluble  in  water. 

Reactions. — When  tartrates  are  heated,  they  are  black- 
ened, and  an  odor  of  burnt  sugar  is  given  off. 

If  a  solution  of  free  tartaric  acid,  that  is  not  too  dilute, 
is  mixed  with  a  solution  of  potassic  acetate,  a  crystalline 
precipitate,  KHC^II^Og,  is  formed  at  once,  or  after  some 
time,  or  after  violent  agitation,  or  addition  of  an  equal 
volume  of  alcohol.  If  the  two  solutions  are  very  concen- 
trated, and  are  stirred  in  a  watch-glass,  a  deposition  of 
crystals  marks  the  track  of  the  rod  over  the  glass. 

Calcic  chloride  gives  a  white  precipitate,  CaC^H^Og,  in 
solutions  of  a  neutral  tartrate,  the  formation  of  which  is 
hastened  by  violent  agitation  ;  the  presence  of  ammonic 
chloride  only  retards  the  appearance  of  the  precipitate, 


§   72.      CITRIC   ACID.  103 

but  does  not  prevent  it.  The  precipitate  is  soluble  in 
boiling  soclic  hydrate,  but  re-precipitation  follows  on 
cooling. 

With  lime-water  in  large  excess,  so  as  to  turn  red  lit- 
mus-paper blue,  tartaric  acid  gives  the  same  white  precipi- 
tate. 

With  calcic  sulphate,  tartaric  acid  in  tartrates  gives  no 
precipitate,  thus  distinguishing  it  from  oxalic  acid. 

With  argentic  nitrate,  neutral  tartrates  give  a  precipi- 
tate that  is  turned  black  when  the  mixture  is  boiled. 

Quantitatiyc  estimation. — An  approximate  determina- 
tion of  tartaric  acid  may  be  made  by  adding  potassic 
acetate  to  its  moderately  concentrated  solution,  and  con- 
siderable alcohol,  collecting  the  precipitate  on  a  weighed 
filter,  washing  it  with  alcohol,  and  drying  it  at  100°  C, 
and  weighing. 

The  residue  of  potassic  tartrate,  KHC^H^Og,  contains 
70.18' |„  of  tartaric  anhydride,  C,H,0,. 

CITRIC  ACID.     H3C6H5O7. 

72.  Citrates  of  barium,  calcium,  and  aluminium,  are 
sparingly  soluble  in  water. 

Reactions. — When  citric  acid  is  heated,  it  fuses  at  first, 
and  then  carbon  is  separated  with  the  evolution  of  pun- 
gent acid  fumes.     Citrates  are  blackened  when  heated. 

Citrates  give  no  precipitate  with  potassic  salts. 

With  lime-water  in  excess,  at  ordinary  temperatures, 
they  give  a  very  slight  precipitate,  which,  on  boiling,  be- 
comes quite  abundant,  but  is  mostly  dissolved  when  the 
mixture  is  cooled. 

Calcic  chloride  gives  a  precipitate  Ca^{Cflfi^)^j  m 
solutions  of  neutral  citrates,  which,  if  obtained  without 
heat,  is  soluble  in  ammonic  chloride ;  it  is  re-precipitated 
from  this  solution  on  boiling,  and  is  not  then  soluble  in 
ammonic  chloride  ;  it  is  insoluble  iu  potassic  hydrate. 


104  §    73.       BASES    AND    ACIDS   WITH    REAGENTS. 

MALIC  ACID.     H2C4H4O5.     134. 

73.  Malate  of  lead  is  difficultly  soluble  in  water 
Reactions; — When  malic  acid  is  heated,  it  froths,  pun- 
gent acid  vapors  being  set  free,  and  crystals  of  maleic  and 
fumaric  acids  are  condensed  in  the  colder  parts  of  the 
tube. 

Malates  give  no  precipitate  with  potassic  salts,  nor 
with  calcic  hydrate  or  sulphate,  even  on  boiling. 

With  calcic  chloride  no  precipitate  is  formed  unless  the 
solution  is  concentrated  and  the  mixture  is  boiled ;  if  this 
precipitate,  CaC^H^O^,2H20,  is  dissolved  in  a  very  little 
hydrochloric  acid,  ammonia  added,  and  the  mixture  boiled, 
the  calcic  malate  is  re-precipitated ;  but  if  it  is  dissolved 
in  considerable  acid,  no  precipitate  is  formed  on  adding 
ammonia  and  boiling ;  alcohol  will  precipitate  the  salt 
from  this  solution. 

Quantitatiye  estimation. — An  approximate  determina- 
tion of  malic  acid  may  be  made  by  adding  calcic  hydrate 
in  excess  to  its  highly  concentrated  solution,  free  from 
citric,  tartaric,  or  sulphuric  acid,  and  then  adding  consid- 
erable alcohol,  collecting  the  precipitate  on  a  dried  and 
weighed  filter,  washing  with  alcohol,  drying  at  100°  C, 
and  weighing. 

The  residue  contains  67.44°|q  of  malic  anhydride, 
C.H.O.. 

LACTIC  ACID.    nCsHsOg.    90. 

74.  All  lactates  are  soluble  in  water ;  only  zincic  lactate 
is  somewhat  difficultly  soluble  in  cold  water. 

Reactions. — Lactates  are  blackened  when  heated. 

If  a  liquid  containing  free  lactic  acid  is  boiled  with  zin- 
cic oxide  or  carbonate,  the  filtered  solution  will  deposit  a 
crystalline  crust  on  its  surface,  or  acicular  crystals,  on 
cooling. 


§   75.      IJEIC  ACID.  105 

Quantitatire  estimation.— This  acid  in  the  free  state 
may  be  determined  by  a  volumetric  process,  the  same  as 
for  the  determination  of  acetic  acid.  The  solution,  free 
from  acetic  or  other  free  acid  except  lactic  acid,  is  titrated 
with  the  standard  sodic  solution.  Each  cubic  centimetre 
of  sodic  solution  required  corresponds  to  0.81  grm.  of  the 
anhydrous  acid,  CgH^^O^. 

To  remove  acetic  acid  as  well  as  carbonic  from  the  so- 
lution, before  estimating  the  lactic  acid,  evaporate  a  por- 
tion of  the  liquid  in  the  water-bath  with  the  addition  of 
pure  quartz  sand  and  with  constant  stirring  towards  the 
end  of  the  operation ;  continue  to  heat  the  dry  residue 
until  no  more  acid  odor  is  given  off,  then  treat  it  with 
water,  filter,  and  wash  the  sand  on  the  filter  as  long  as  the 
washings  are  acid,  and  determine  lactic  acid  in  the  filtrate 
with  the  standard  sodic  solution  as  above. 

URIC  ACID.  H3CgH2N403  +  4aq.     304. 

75.  This  acid  is  but  slightly  soluble  in  water,  and  is 
insoluble  in  alcohol.  Alkaline  urates  are  soluble  in  water ; 
others  are  insoluble. 

Reactions. — If  uric  acid  or  a*  urate  is  heated  with  mod- 
erately strong  nitric  acid,  the  mixture  filtered  if  not  clear, 
the  filtrate  carefully  evaporated  to  dryness,  and  the  resi- 
due moistened  with  ammonia,  a  beautiful  purple  color 
(murexide)  appears. 

In  urinary  sediments,  uric  acid  may  often  be  recognized 
under  the  microscope  by  the  rhombic  six-sided  plates,  or 
right-angled  four- sided  prisms  of  a  brown  to  a  golden  yel- 
low color,  which  it  forms. 

Quantitative  estimation. — ^Precipitate  the  uric  acid 
from  the  solution  containing  it  by  the  addition  of  hydro- 
chloric acid,  if  no  albumen  is  present ;  in  case  it  is  pres- 
ent, use  acetic  or  phosphoric  acid  instead  of  hydrochloric. 
Let  the  mixture  stand  36-48  hours,  and  collect  the  pre- 


106  76.       BASES    AND   ACIDS    WITH    REAGENTS. 

cipitated  acid  on  a  dried  and  weighed  filter,  and  add  0.045 
mgr.  to  the  amount  of  uric  acid  found,  for  every  cubic 
centimetre  of  wash-water  passed  through  the  filter. 

If  hippuric  acid  was  present,  it  must  be  dissolved  out 
of  this  precipitate  by  treating  it  several  times  with  alco- 
hol of  83"  |„. 

HIPPURIC  ACID.    HCsH^NOs.     179. 

76.  This  acid  is  slightly  soluble  in  cold  water,  but 
readily  soluble  in  boiling  water  and  in  alcohol,  and  slight- 
ly soluble  in  ether. 

Ferric  and  plumbic  hippurates  are  quite  insoluble  in 
water ;  all  others  are  soluble. 

Quantitative  estimation. — Precipitate  the  concentrated 
solution  of  the  acid  with  hydrochloric  acid,  and  let  the 
mixture  stand  in  the  cold  48  hours ;  collect  the  precipitate 
on  a  dried  and  weighed  filter,  wash  it  with  small  portions 
of  very  cold  water,  until  the  washings  are  colorless  and 
give  only  a  faint  turbidity  with  argentic  nitrate,  dry  at 
100°,  and  weigh.  For  every  6  c.c.  of  wash-water  tliat 
passed  through  the  filter  add  0.01  grm.  to  the  amount  of 
hippuric  acid  found. 

If  uric  acid  is  present,  the  precipitate,  after  being 
weighed,  must  be  treated  with  alcohol,  and  the  residue  of 
uric  acid  weighed  again.  The  difference  between  the  two 
weights  will  be  the  hippuric  acid. 

For  a  better  method  of  separating  the  two  acids  see 
urine,  §  113,  A. 

TANNIC  ACID. 

77.  Tannic  acid  is  soluble  in  water,  alcohol,  and  ether ; 
alkaline  tannates  are  soluble  in  water,  but  others  are  difii- 
cultly  soluble. 

Reactions. — Tannic  acid  gives  a  violet-black    precipi- 


77.       TANNIC    ACID.  107 

tate  with  ferric  salts.  It  also  gives  a  white  precipitate 
when  poured  into  a  solution  of  gelatine ;  as  long  as  the 
gelatine  is  in  excess,  this  precipitate  is  soluble  in  the  sn- 
pernatant  liquor  when  heated,  while  if  the  acid  is  in  ex- 
cess, it  is  much  less  soluble. 

If  a  piece  of  fresh  skin,  deprived  of  its  hair  by  caustic 
lime,  is  left  for  several  hours  in  contact  with  a  solution 
of  tannic  acid,  the  latter  is  completely  absorbed,  so  that 
the  liquid  will  give  no  color  with  ferric  salts. 

Quantitatiyc  estimation. — The  tannic  acid  in  a  solution 
may  be  determined  with  considerable  accuracy  by  com- 
paring the  specific  gravity  of  the  solution  before  and 
after  it  has  been  in  contact  with  j^ow^dered  skin. 

The  solution  must  be  as  clear  as  possible  and  not  too 
dilute ;  such  a  one  will  answer,  for  example,  as  may  be 
obtained  by  exhausting  20  to  40  grms.  of  tanner's  bark 
with  water,  and  diluting  to  400  or  500  c.c. 

Detei-mine  the  weight  of  the  extract  obtained  from  a 
w^eighed  quantity  of  the  bark,  and  then  determine  the 
specific  gravity  of  the  solution  accurately  with  the  pik- 
nometer,  or  specific-gravity  bottle  (§  34,  a).  Then  weigh 
out  100  c.c.  of  the  solution  in  a  flask,  and  weigh  out  also 
a  quantity  of  finely  divided  skin,  equal  to  about  four 
times  the  amount  of  tannic  acid  that  is  supposed  to  be  in 
this  quantity  of  the  solution ;  this  amount  can  be  ascer- 
tained approximately  from  Table  lY,  taking  as  the  per 
cent  of  tannic  acid  that  which  is  found  against  the 
number  representing  the  specific  gravity  of  the  original 
solution,  just  determined. 

Soften  the  skin  by  soaking  it  in  -water,  enclose  it  in  a 
linen  bag  and  press  out  the  water,  add  it  to  the  weighed 
solution  in  the  flask,  close  the  flask  and  shake  the  mix- 
ture vigorously,  filter  through  a  linen  cloth  and  determine 
the  specific  gravity  of  the  filtrate.  To  the  difference  be- 
tween the  specific  gravity  before  and  after  treatment  with 
the  skin,  add  one,  seek  for  the  number  so  obtained  in  the 


108  78.       BASES    AND    ACIDS    WITH    REAGENTS. 

column  headed  specific  gravity  at  15°  C,  in  Table  lY, 
and  against  that  will  be  found  the  per  cent  of  tannic  acid 
in  the  solution  examined.  A  simple  calculation  will  then 
give  the  per  cent  of  the  acid  in  the  bark. 

To  prepare  the  powder  of  skin  required  in  this  analy- 
sis, wash  a  piece  of  skin,  that  has  been  prepared  for 
tanning  by  treatment  with  lime  and  other  agents,  with 
water,  stretch  it  on  a  board,  dry  it  with  the  aid  of  a  gentle 
heat,  and  rasp  it  with  a  coarse  file.  Keep  the  powder  in 
a  well  stoppered  bottle. 

CELLULOSE.     C12H20O10.        324. 

78.  Cellulose  is  insoluble  in  water,  dilute  acids  or  al- 
kalies, alcohol,  ether,  or  oils.  It  is  soluble  in  an  ammonic 
solution  of  cupric  oxide,  and  is  precipitated  from  this  so- 
lution in  the  form  of  colorless  flakes. 

Strong  sulphuric  acid,  composed  of  four  j^arts  of  acid  and 
one  of  water,  disintegrates  it  at  ordinary  temperatures 
without  coloring  it,  and,  after  a  time,  changes  it  into 
dextrine.  With  iodine  solution  this  disintegrated  cellulose, 
before  its  passage  into  dextrine,  gives  a  violet-blue  color. 

Quantitative  estimation. — Cellulose  is  estimated  quan- 
titatively by  freemg  it  as  completely  as  possible  from  all 
other  substances,  and  weighing  the  residue  as  pure  cellu- 
lose ;  the  best  method  yields  results,  however,  that  are 
about  l^lo  too  high. 

A  quantity  of  3  to  4  grms.  of  the  substance  is  exhaust- 
ed with  water,  alcohol,  and  ether,  successively,  as  long  as 
each  of  these  solvents  takes  anything  into  solution,  and 
is  then  macerated  10  or  12  days  in  a  glass-stoppered  bot- 
tle, at  a  temperature  not  above  15°  C,  with  12  grms,  of 
nitric  acid  (Sp.  Gr.  =  1.1),  and  0.8  grm.  of  potassic  chlo- 
rate ;  water  is  then  added,  the  mixture  is  filtered,  and 
the  filter  is  well  washed,  first  with  cold  and  afterwards 
with  hot  water :  the  contents  of  the  filter  are  then  rinsed 


79.      STAKCH.  109 

into  a  beaker  and  digested  about  an  hour,  at  60°  C,  with 
ammoniacal  water  containing  50  parts  of  water  to  one  of 
common  ammonia  ;  the  mixture  is  filtered  through  a  dried 
and  weighed  filter,  the  contents  of  the  filter  washed  with 
the  same  ammoniacal  water  until  the  washings  are  color- 
less, then  with  pure  water,  with  alcohol,  and  finally  with 
ether,  dried  at  100°  C,  and  weighed. 

This  cellulose  often  contains  as  much  as  from  0.5  to  0.7 
"  lo  of  albuminoids,  and  a  very  small  per  cent  of  inorganic 
matters. 

STARCH.     C12H20O10.        324. 

79i  Starch,  as  long  as  it  retains  its  natural  form,  is  in- 
soluble in  water,  alcohol,  and  ether.  In  contact  with  hot 
water  the  starch  grains  swell  up,  and,  if  a  larger  quantity 
of  water  is  then  added,  a  small  portion  of  the  starch  re- 
mains in  solution. 

Starch  may  be  converted  into  a  soluble  modification  by 
boiling  it  with  water  under  pressure,  by  heating  it  a  short 
time  with  dilute  sulphuric  acid,  or  by  the  action  of  dias- 
tase at  ordinary  temperatures. 

Dry  starch  is  colored  blue  or  black  by  a  solution  of 
iodine  in  potassic  iodide.  The  color  is  destroyed  by  alco- 
hol, potassa,  or  hydrosulphuric  acid,  or  by  heat ;  if  not 
heated  too  long,  the  blue  color  reappears  as  the  solution 
cools. 

Quantitative  estimation. — Starch  is  usually  determined 
by  conversion  into  glucose,  either  by  malt  or  sulphuric 
acid,  and  the  subsequent  determination  of  the  glucose 
with  Fehling's  solution. 

1.  By  malt. — To  prepare  the  extract  of  malt,  crush  6 
grms.  of  fresh  malt  in  a  mortar,  digest  with  lukewarm 
water,  filter,  and  wash  the  filter  with  water  of  60°  or  70°, 
and  divide  the  clear  filtrate,  after  mixing  it  well  with  the 
washings,  into  two  exactly  equal  parts.     Mix  a  quantity 


110  79.       BASES    AXD   ACIDS    WITH    REAGENTS. 

of  the  substance  to  be  examined  containing  about  2.5 
grms.  of  starch  with  water,  heat  to  70°  C,  add  one  of  the 
portions  of  the  extract  of  malt,  put  the  other  portion  into 
another  flask,  and  digest  both  precisely  alike  3  or  4  hours 
on  the  water-bath,  at  a  temperature  of  about  60°  or  70° 
C.  Then  bring  both  liquids  to  about  200  c.c.  by  addition 
of  water,  add  20  c.c.  of  a  solution  of  basic  plumbic  ace- 
tate (§  24,  a)  to  each,  shake  vigorously,  add  water  again 
until  the  volume  of  each  liquid  is  exactly  500  c.c,  at  a 
temperature  of  nearly  15°,  let  the  mixture  stand  until  tlie 
solid  matters  settle,  and  then  determine  the  glucose  in  an 
aliquot  j^art  of  each  liquid  with  the  aid  of  the  standard 
Fehling's  solution  (§  81).  10  c.c.  of  that  solution  corres- 
pond to  0.045  grm.  of  starch.  The  two  liqujds  will  con- 
tain equal  quantities  of  glucose,  produced  from  the  malt ; 
therefore,  the  difference  between  the  amounts  of  glucose 
found  in  the  two,  or  the  corresponding  difference  between 
the  amounts  of  starch,  will  be  the  amount  of  starch  in 
the  substance  analyzed. 

2.  a.  ^y  sulphuric  acid. — ^Dry  the  substance  thoroughly, 
and  digest  a  quantity  of  it,  supposed  to  contain  about  2.5 
grms.  of  starch,  2  hours  on  the  water-bath,  with  50  times 
its  weight  of  a  dilute  sulphuric  acid,  containing  1°!^,  by 
volume  of  concentrated  acid,  then  filter,  and  wash  the 
residue  on  the  filter  carefully.  This  residue  is  composed 
mostly  of  cellulose.  Dilute  the  filtrate  and  washings  to 
200  c.c,  add  about  IG  c.c.  of  concentrated  sulphuric  acid, 
and  digest  again  7  or  8  hours  on  the  water-batli,  at  95°, 
or  until  a  drop  of  the  solution  gives  no  blue  color  with  a 
solution  of  iodine.  If  the  solution  is  highly  colored,  add 
20  c.c.  of  plumbic  acetate,  shake  vigorously,  make  the 
volume  of  the  liquid  up  to  500  c.c,  let  the  mixture  stand 
if  it  is  necessary  to  clarify  the  solution,  and  determine  the 
glucose  in  the  clear  supernatant  liquid  with  the  standard 
Fehling's  solution,  10  c.c.  of  which  correspond  to  0.045 
grm.  of  starch  (§  81). 


79.       STARCH.  Ill 

The  process  of  previous  digestion  with  a  more  dilute 
acid  separates  the  starch  more  completely  from  the  cellu- 
lose, the  former  being  converted  into  the  soluble  modifica- 
tion, while  the  latter  remains  unchanged.     {Krocker.) 

h.  Wolff's  process.— 'Dx^Q^X,  2.5  to  4  grms.  of  the  sub- 
stance with  100  c.c.  of  water,  and  12  to  16  drops  of  con- 
centrated acid,  24  hours  on  the  water-bath,  then  seal  the 
liquid  up  in  glass  tubes  and  heat  12  hours  in  an  oil-bath  to 
120°  C,  then  dilute,  decolorize  with  plumbic  acetate,  and 
so  on  as  directed  in  a, 

3.  Dragendorff  gives  the  following  method  for  separat- 
ing and  determining  starch  and  the  other  matters  with 
which  it  is  usually  associated. 

Pulverize  about  2.5  grms.  of  the  substance  that  has  been 
dried  at  100°,  mix  the  powder  with  about  30  grms.  of  a 
solution  of  about  6  parts  of  i3otassic  hydrate  in  95  parts  of 
absolute  alcohol,  and  digest  the  mixture  24  hours  at  100°  C. 
in  a  sealed  tube,  or  in  a  flask  that  can  be  closed  air-tight ; 
filter  the  contents  of  the  flask,  while  hot,  through  a  dried 
and  weighed  filter,  wash  the  residue  thoroughly,  first  with 
hot  absolute  alcohol,  then  with  cold  alcohol  of  ordinary 
strength,  and  finally  with  distilled  water,  mixed  with  a 
little  alcohol  if  gummy  substances  are  present  in  notable 
quantity,  dry  the  filter,  first  at  50°,  and  then  at  100°,  and 
weigh.  The  difference  between  this  weight  and  that  of 
the  substance  taken  gives  the  amount  of  albuminoids,  fat, 
sugar,  and  a  part  of  the  mineral  salts. 

The  insoluble  residue,  with  the  filter  torn  in  shreds,  is 
heated  with  water  containing  S"!,,  of  hydrochloric  acid 
until  a  drop  of  the  liquid  gives  no  blue  color  with  solution 
of  iodine,  the  mixture  is  filtered  ao:ain  throuG:h  a  dried 
and  weighed  filter,  dried  at  100°,  and  v/eighed.  The  sec- 
ond loss  of  weight  gives  the  amount  of  starch ;  it  was 
converted  into  dextrine  by  the  acid  and  dissolved  out ; 
a  very  small  quantity  of  mineral  matters  might  pass  into 
solution    also,   and,  if  great    accuracy    is   required,  the 


112  §    80.       BASES    AND    ACIDS    WITH   REAGENTS. 

amount  of  these  can  be  determined  by  evaporating  the 
solution  of  starch  and  inorganic  salts  to  dryness,  and  in- 
cinerating the  residue  at  a  low  red  heat  (§  91). 

Or,  the  starch  may  be  extracted  with  a  concentrated 
solution  of  malt  instead  of  with  acid,  in  wliich  case  no  in- 
organic salts  will  be  taken  into  solution.  Prepare  the 
solution  of  malt  and  perform  the  operation  as  directed 
above. 

If  much  mucus  is  present,  a  concentrated  solution  of 
sodic  chloride  mixed  with  6°\^  of  hydrochloric  acid  should 
be  used  instead  of  pure  water  and  acid. 

GUM. 

80.  The  gums,  which  abound  in  the  juices  of  plants, 
are  very  soluble  in  water,  forming  thick,  viscid  solutions ; 
they  are  insoluble  in  alcohol. 

Quantitative  estimation. — This  depends  upon  their  in- 
solubility in  alcohol.  A  quantity  of  from  500  to  1000  c.c. 
of  the  aqueous  extract  of  the  substance  in  which  the  gum 
is  to  be  determined  is  evaporated  almost  to  dryness  on 
the  water-bath,  and  the  moist  residue  is  digested  with  al- 
cohol of  80  to  85"  |„  until  it  is  no  longer  colored  by  mat- 
ters taken  into  solution. 

Sugar  is  dissolved,  while  gum,  albuminoids,  and  some 
inorganic  salts,  remain  unaffected ;  collect  the  insoluble 
substance  on  a  dried  and  weighed  filter,  dry  at  100°  C, 
and  weigh.  Then  incinerate  this  residue  at  a  low  red  heat 
(§  91),  and  subtract  from  the  total  weight  of  the  residue 
insoluble  in  alcohol,  the  sum  of  the  weights  of  the  ash 
just  determined,  and  the  albuminoids,  which  are  deter- 
mined by  another  process  (§  85).  The  remainder  may  be 
considered  as  gum,  mixed  with  some  vegetable  acids. 

GLUCOSE.    GRAPE  SUGAR.     CeHi^OeHaO.        180  +  18. 

81 .  This  sugar  is  soluble  in  water,  and  somewhat  solu- 
ble in  aqueous  alcohol. 


§    81.       GLUCOSE.  113 

It  is  colored  dark  brown  when  heated  with  a  strong  so- 
lution of  sodic  hydrate. 

If  triturated  Avith  cold  concentrated  sulphuric  acid,  it 
is  dissolved  without  being  blackened. 

If  a  concentrated  solution  of  glucose  is  mixed  with  co- 
baltic  nitrate  and  a  small  quantity  of  fused  caustic  soda, 
the  solution  remains  clear  on  being  boiled. 

If  baric  hydrate  is  added  to  an  alcoholic  solution  of 
sugar,  a  white  precipitate  is  formed. 

If  a  little  caustic  soda  is  added  to  a  solution  of  glucose, 
and  then,  drop  by  drop,  a  dilute  solution  of  cupric  sul- 
phate, a  deep  blue  liquid  is  formed ;  but  after  a  few  mo- 
ments a  yellowish  or  red  precipitate  of  hydrated  cuprous 
oxide  is  separated.  A  solution  containing  0.00001  of  glu- 
cose will  give  a  notable  red  precipitate  on  the  addition  of 
soda  and  a  few  drops  of  cupric  sulphate ;  0.000001  of  glu- 
cose in  the  solution  gives  a  red  tint  to  it  with  the  above 
reagents. 

Quantitatiye  estimation. — This  may  be  effected  by 
making  use  of  the  delicate  reaction  just  described.  One 
equivalent  of  glucose  will  reduce  ten  equivalents  of  cupric 
oxide  to  cuprous  oxide ;  if,  then,  we  know  the  quantity 
of  cupric  oxide  that  has  been  reduced,  we  can  calculate 
the  corresponding  amount  of  sugar.  For  this  determina- 
tion, a  standard  solution  of  cupric  oxide  containing  an 
excess  of  alkali  is  commonly  used,  or  Fehling's  solution, 
as  it  is  often  called. 

Dissolve  34.639  grms.  of  pure,  crystallized  cupric  sul- 
phate in  about  200  c.c.  of  water ;  make  another  solution 
of  173  grms.  of  pure,  crystallized  potassic  sodic  tartrate 
in  480  c.c.  of  a  solution  of  sodic  hydrate  (Sp.  Gr.  =  1.14). 
Add  the  first  solution  gradually  to  the  second,  and  dilute 
the  mixture  to  1000  c.c.  Each  10  c.c.  of  this  solution 
corresponds  to  0.05  grm.  of  glucose.  Keep  the  solution 
in  small,  well-stoppered  bottles,  in  a  dark  place  ;  the  bot- 


114  §    81.       BASES    AND    ACIDS    WITH    REAGENTS. 

ties  should  be  filled  to  the  top,  so  that  no  carbonic  acid 
can  be  absorbed. 

Before  using  the  solution,  boil  about  10  c.c.  of  it  with 
about  40  c.c.  of  water,  or  of  a  dilute  solution  of  sodic  hy- 
drate if  there  is  any  reason  to  believe  that  carbonic  acid 
has  been  absorbed ;  there  should  not  be  the  least  change 
in  the  liquid  when  subjected  to  this  trial. 

To  perform  the  analysis,  put  10  c.c.  of  the  cuprlc  solu- 
tion in  a  porcelain  dish,  and  add  40  c.c.  of  water,  or  of  a 
solution  of  sodic  hydrate  if  it  was  found  necessary  to 
add  this  in  testing  the  solution  ;  heat  the  mixture  until  it 
boils  gently,  and  allow  the  sugar  solution,  which  should 
be  colorless  and  not  acid,  and  should  not  contain  more 
than  ^1^  to  ^|/|g  of  sugar,  to  drop  in  from  a  burette  or  a 
pipette,  graduated  into  ^\^^  c.c,  so  slowly  that  the  boiling 
will  not  be  stopped.  After  the  addition  of  the  first  few 
drops,  the  fluid  shows  a  greenish-brown  tint ;  as  more  sug- 
ar solution  is  added,  the  precipitate  becomes  more  copi- 
ous, acquires  a  reddish  tint,  and  subsides  more  speedily  j 
when  it  presents  a  deep  red  color,  remove  the  lamp,  allow 
the  precipitate  to  settle,  and  give  the  dish  an  inclined 
position,  so  that  the  color  of  the  supernatant  liquid  can 
be  more  readily  distinguished  over  the  white  porcelain 
surface  ;  if  no  blue  or  bluish-green  color  is  seen,  probably 
enough  of  the  solution  of  sugar  has  been  added.  To  be 
sure,  test  a  small  portion  of  tbe  clear  liquid  with  a  drop 
of  the  solution  from  the  burette ;  if  a  yellowish-red 
precipitate  appears  on  heating,  which,  at  first,  may 
look  like  a  cloud  in  the  liquid,  pour  the  contents  of  the 
tube  back  into  the  dish  again,  and  continue  to  add  the 
sugar  solution  until  the  reaction  is  completed.  Then 
the  solution  in  the  dish  should  contain  neither  copper  nor 
sugar,  nor  a  brown  product  resulting  from  the  decompo- 
sition of  the  latter ;  filter  ofl*  a  portion  of  it  while  still 
hot ;  the  filtered  liquid  should  have  no  brown  tinge  ;  one 
portion,  heated  with  a  drop  of  the  standard  cupric  solu- 


§    82.       LEYULOSE.       §    83.       SACCHAROSE.  115 

tion,  should  produce  no  change  in  it ;  another  poition 
should  give  no  red  coloration  or  precipitate  with  potassic 
ferrocyanide.  nor  a  black  one  with  amnionic  sulphide.  If 
these  tests  do  not  indicate  a  satisfactory  termination  of 
the  analysis,  it  should  be  repeated  with  a  fresh  quantity 
of  10  c.c.  of  the  cupric  solution. 

The  amount  of  solution  of  sugar  required  to  reduce  the 
cupric  oxide  in  this  quantity  of  the  cupric  solution  con- 
tained 0.05  grm.  of  glucose. 

Generally,  the  first  result  obtained  is  only  an  approxi- 
mation ;  in  the  second  trial,  add  at  once  nearly  the  whole 
amount  of  sugar  solution  required,  and  then  test  the  liquid 
after  each  addition  of  two  drops  at  a  time.     {Fresenius.) 

LEVULOSE.     FRUIT  SUGAR.     CeHi^Oe. 

82*  This  sugar  is  Tery  soluble  in  Avater  and  aqueous 
alcohol.  It  behaves  like  glucose  with  an  alkaline  cupric 
solution,  and  is  determined  quantitatively  in  the  same 
manner. 

SACCHAROSE.     CANE  SUGAR.     C12H22O11.    342. 

83.  This  sugar  is  more  soluble  in  water  and  aqueous 
alcohol  than  glucose. 

It  is  not  turned  brown  by  strong  alkaline  solutions. 

If  triturated  with  cold  concentrated  sulphuric  acid,  it 
is  turned  black,  and  sulphurous  acid  is  evolved. 

If  a  concentrated  solution  of  saccharose  is  mixed  with 
cobaltic  nitrate  and  a  small  quantity  of  fused  caustic 
soda,  and  boiled,  a  violet-blue  precipitate  is  formed.  The 
presence  of  a  very  small  quantity  of  glucose  prevents  the 
formation  of  this  precipitate. 

If  sodic  hydrate  is  added  to  a  solution  of  saccharose, 
and  a  few  drops  of  cupric  sulphate,  a  deep  blue  solution 
is  obtained  that  remains  unchanged  on  standing  in  the 
cold  ;  if  the  sodic  hydrate  is  largely  in  excess,  the  solution 
can  be  boiled  a  short  time  without  change. 


116  §    84.       BASES    AND    ACIDS    WITH   EKAGENTS. 

Saccharose  is  converted  into  glucose  and  levulose  when 
heated  with  very  dilute  sulphuric  acid,  by  treatment  with 
yeast,  or  even  by  long  boiling  of  its  aqueous  solution  alone. 

Quantitatiye  estimation. — This  may  be  effected  by  first 
converting  the  saccharose  into  glucose  and  levulose,  and 
then  determining  the  amount  of  these  with  the  standard 
cupric  solution. 

The  solution,  containing  about  2.5  grms.  of  saccharose, 
is  diluted  to  about  250  c.c,  12  drops  of  concentrated  sul- 
phuric acid  are  added,  and  the  mixture  is  heated  3  hours 
on  the  water-bath,  with  renewal  of  the  water  as  it  is 
evaporated  (§  36).  If,  after  this  operation,  the  solution 
has  a  dark  color,  as  may  often  be  the  case,  add  20  c.c.  of 
the  solution  of  j)lumbic  acetate  (§  24,  a),  shake  the  mix- 
ture well,  dilute  to  exactly  500  c.c,  let  it  stand  awhile, 
and  use  the  clear  supernatant  liquid  for  the  determination 
of  glucose  (§  81). 

If  it  does  not  need  clarifying  with  plumbic  acetate,  neu- 
tralize the  free  acid  with  sodic  carbonate,  dilute  to  exactly 
500  c.c,  and  determine  glucose  as  above. 

10  c.c.  of  the  standard  cupric  solution  correspond  to 
0.0475  grm.  of  saccharose. 

In  case  a  solution  contains  both  glucose  and  saccharose, 
and  it  is  desired  to  determine  the  amount  of  each,  esti- 
mate the  glucose  at  once  by  titration  with  the  cupric  so- 
lution ;  then  convert  the  saccharose  into  glucose,  as  above, 
and  titrate  the  solution  again ;  the  last  determination 
gives  the  sum  of  the  glucose  originally  in  the  solution 
and  that  which  was  derived  from  the  saccharose. 

LACTOSE.     MILK  SUGAR.     CasHaiOja. 

84.  This  sugar  is  soluble  in  water,  but  not  in  cold 
alcohol. 

It  reduces  an  alkaline  solution  of  cupric  oxide  like  glu- 
cose, but  in  a  different  proportion.  It  is  converted  into 
glucose  by  dilute  acids. 


§    85.       ALBUMINOIDS    OR  PROTEIN   COMPOUNDS.       117 

Quantitative  estimation. — Convert  it  into  glucose  by 
digesting  its  solution  about  2  hours  with  a  little  sulphuric 
acid,  and  then  determine  the  glucose  with  the  standard 
cupric  solution. 

10  c.c.  of  the  solution  correspond  to  0.05  grm.  of 
lactose. 

ALBUMINOIDS  or  PROTEIN  COMPOUNDS. 

85.  Some  of  these  substances  are  soluble  in  water, 
others  are  insoluble.  Most  metallic  salts  precipitate  them 
from  their  solutions,  or  coagulate  the  solutions,  as  it  is 
termed. 

All  of  them  are  dissolved  by  boiling  concentrated  hy- 
drochloric acid,  and  the  solution  takes  a  violet  color  if 
access  of  air  is  allowed. 

All  of  them  are  colored  yellow  by  concentrated  nitric 
acid,  and  by  iodine. 

They  are  colored  red  by  a  solution  of  mercuric  nitrate 
(Millon's  test)  ;  this  is  the  most  delicate  test  for  these 
bodies  ;  albumen,  dissolved  in  100,000  parts  of  water, 
may  be  detected  by  this  reagent. 

If  a  small  quantity  of  an  albuminous  substance  is  treat- 
ed with  dilute  potassic  hydrate,  one  or  two  drops  of  a 
dilute  solution  of  cupric  sulphate  added,  and  more  potassa 
until  the  mixture  is  alkaline,  and  the  whole  is  well  mixed 
together,  a  violet  precipitate  appears,  which  dissolves  after 
a  little  agitation ;  in  the  presence  of  a  carbo-hydrate,  as 
sugar  or  starch,  the  color  is  bluish,  and  the  blue  tint  is 
deeper,  the  more  of  the  carbo-hydrate  is  mixed  with  the 
albuminoid.     {Journal  far  Frakt.  Chemie,  102,  376.) 

When  heated,  these  substances  give  off  the  odor  of 
burnt  horn  or  hair. 

Distinctive  reactions.— ^^S^^^e^  is  precipitated  when 
its  neutral  solutions  are  heated  to  70°  C,  or  the  solution  is 
coao-ulated ;  if  alkaline,  the  solution  needs  to  be  neutral- 


118  §    85.       BASES    AND    ACIDS    WITH   EE AGENTS. 

ized  by  acetic  acid  before  this  reaction  can  be  obtained ; 
if  the  solution  is  very  dilute,  the  presence  of  albumen 
will  be  shown  by  a  flocculent  precipitate,  or  a  mere  tur- 
bidity, on  being  boiled.  A  solution  of  albumen  is  coagu- 
lated also  by  plumbic  acetate  or  cupric  sulphate,  but  not 
by  acetic  acid. 

Casein  is  not  precipitated  from  its  solutions  by  heat, 
except  that  a  film  is  formed  on  the  surface  of  the  boiling 
liquid ;  it  is  precipitated  by  acetic  and  other  acids,  and 
the  precipitate  is  soluble  in  an  excess  of  acetic  acid. 

Fibrine  is  precipitated  from  its  solutions  spontane- 
ously, when  they  are  removed  from  the  influence  of  vital 
forces. 

Quantitative  estimation. — As  it  is  almost  impossible  to 
separate  all  of  an  albuminoid  from  its  solution  or  from 
matters  mixed  with  it,  pure  and  unaltered,  or  in  the  form 
of  any  insoluble  precipitate  of  a  definite  composition,  the 
amount  of  albuminous  matters  in  a  substance  is  usually 
estimated  froiji  the  amount  of  nitrogen  in  it. 

Albuminoids  contain,  on  an  average,  16°  1^  of  nitrogen; 
therefore,  the  total  weight  of  the  albuminoid  is  VV  —  6.25 
times  that  of  its  nitrogen.  Assuming,  then,  what  is  gen- 
erally true,  that  all  the  nitrogen  present  in  the  dried 
plant  is  part  of  an  albuminoid,  we  multiply  the  weight 
of  nitrogen  found  in  the  substance  by  6.25  for  the  weight 
of  the  albuminoids. 

Determination  of  Nitrogen. — The  method  most  gener- 
ally applied  in  this  case,  as  well  as  in  agricultural  analyses 
generally,  is  that  of  Yarentrapp  and  Will,  as  modified  by 
Pehgot,  in  which  the  nitrogen  is  converted  into  ammonia 
by  ignition  with  soda-lime,  and  the  ammonia  is  absorbed 
by  a  measured  quantity  of  a  standard  acid ;  the  ignition 
is  performed  in  a  thick-walled  tube  of  hard  Bohemian 
glass,  about  40  cm.  long,  and  12  mm.  in  diameter,  drawn 
out  into  a  slender  beak  at  one  end  that  is  bent  upwards. 


§    85.       DETERMINATION    OF   NITROGEN.  119 

a.  First  clean  and  dry  the  tube  thoroughly,  and  seal  up 
the  point  of  the  beak ;  then  put  in  the  throat,  where  the 
beak  widens  out  into  the  tube,  a  loose  plug  of  freshly  ig- 
nited asbestus ;  rinse  the  tube  out  with  a  little  soda-lime, 
about  half  fill  it  with  the  same  reagent,  freshly  io-nited 
and  still  warm,  empty  this  soda-lime  into  a  warm,  dry 
mortar,  and  mix  intimately  with  it,  by  gentle  trituration, 
without  much  pressure,  a  carefully  weighed  quantity  of 
from  0.2  to  0.5  grm.  of  the  finely  powdered  and  well- dried 
substance ;  the  quantity  to  be  taken  depends  upon  the 
richness  of  the  substance  in  nitrogen ;  fill  about  3  cm.  of 
the  tube  with  soda-lime,  and  transfer  this  mixture  into  it 
from  the  mortar,  by  scooping  it  up  carefully  with  the 
open  end  of  the  tube,  over  a  sheet  of  dark-colored  glazed 
paper ;  carefully  rinse  the  mortar  and  pestle  into  the  tube 
with  several  small  portions  of  the  soda-lime,  and  finally, 
when  the  tube  is  filled  to  within  about  4  cm.  of  the  end, 
close  it  with  another  plug  of  freshly  ignited  asbestus,  and 
rap  it  gently  on  the  table  several  times,  in  order  to  se- 
cure an  open  space  in  the  upper  part  of  it  for  the  passage 
of  gases. 

h.  In  some  cases,  as  in  the  analysis  of  Peruvian  guano 
for  example,  the  evolution  of  ammonia  is  liable  to  begin 
as  soon  as  the  substance  and  soda-lime  are  brought  to- 
gether. If  there  is  danger  of  this,  fill  about  10  cm.  of 
the  tube  with  soda-lime,  which  should  be  but  very  slightly 
warm,  if  at  all,  then  put  in  the  substance,  fill  10  cm.  more 
with  the  reagent,  and  mix  the  two  together  as  rapidly  as 
possible  by  means  of  a  wire,  bent  in  the  form  of  a  cork- 
screw at  the  end ;  if  this  is  moved  backwards  and  for- 
wards, and  twisted  round  a  few  times,  through  the  sub- 
stance and  the  soda-lime,  a  very  perfect  mixture  can  be 
quickly  made ;  before  taking  the  wire  out,  put  in  about 
10  cm.  more  of  soda-lime,  and  work  the  corkscrew  back 
and  forth  through  this  to  clean  it,  and  then  fiinish  filling 
the  tube  as  in  a. 


120 


85. 


BASES    AND    ACIDS    WITH    REAGENTS. 


With  the  aid  of  the  burette,  put  20  c.c.  of  the  standard 
sulphuric  acid  in  the  bulbed  tube  C  (fig.  5),  and  add 
water  until  the  bulbs  are  about  'I3  filled ;  the  quantity  of 
the  liquid  should  not  be  so  great,  however,  as  to  incur  any 
danger  of  loss  when  the  gases  evolved  from  the  combus- 
tion-tube pass  rapidly  through,  or  when,  as  sometimes 
B  A 


Fig.  5. 

happens,  there  is  a  sudden  retrograde  current  towards  the 
combustion-tube  at  the  close  of  the  operation. 

When  the  bulbed  tube  is  properly  filled,  hold  it  so  that 
the  liquid  rises  higher  in  one  arm  than  in  the  other,  con- 
nect it  with  the  combustion-tube  by  the  soft,  well-fitting 
cork,  that  has  been  already  fitted  to  the  small  horizontal 
tube  of  the  bulbed  apparatus,  and  lay  the  combustion- 
tube  on  a  level  table  ;  if  the  connection  is  not  tight,  the 
acid  will  slowly  assume  the  same  level  in  both  arms  of 
the  bulbed  tube. 

The  apparatus  being  tight  throughout,  and  a  small  fur- 
nace full  of  live  charcoal  coals  being  ready,  the  combus- 
tion-tube is  introduced  into  the  iron  combustion-furnace 
(fig.  5),  so  that  only  about  5  cm.  of  the  tube  remains  out- 
side the  furnace  at  B,  and  the  whole  is  slightly  inclined 
towards  that  end,  so  that  any  water,  condensing  in  the 
small  tube  of  the  bulbed  apparatus,  will  flow  down  into 
the  bulb  beyond. 

A  movable  screen  benig  placed  over  che  tube  in  the 
fm-nace,  about  8  cm.  from  the  end  B,  this  end  is  surround- 


§    85.       DETEEMIITATION    OF   NITEOGEN.  121 

ed  with  fresh,  live  coals,  large  coals  being  used  to  brido-e 
over  the  top,  in  order  that  there  shall  be  no  weight  there 
on  the  tube  Avhen  softened  by  heat,  to  bend  it  inwards 
and  close  the  passage  above  the  soda-lime. 

When  this  part  of  the  tube  is  red-hot,  move  the  screen 
along  about  8  cm.,  and  apply  more  coals  in  the  same  man- 
ner as  around  the  first  8  cm.  of  the  tube. 

When  that  part  of  the  tube  is  approached,  where  the 
mixture  of  soda-lime  and  substance  is  contained,  care 
must  be  exercised  in  applying  the  coals,  so  as  not  to  have 
too  rapid  an  evolution  of  the  gas  ;  there  is  little  danger 
that  any  ammonia  Avill  pass  through  the  acid  unabsorbed, 
but  it  will  be  safer  not  to  have  so  rapid  a  flow  of  gases  that 
the  bubbles  in  the  bulbed  apparatus  cannot  be  counted  ; 
nevertheless,  a  continuous  current  should  be  maintained, 
and,  all  the  while,  the  front  end  of  the  tube  must  be  kept 
well  heated  by  supplying  fresh  coals  as  often  as  is  nec- 
essary. 

When  the  tube  has  been  heated  throughout,  and  quite 
intensely  around  the  mixture  of  substance  and  soda-lime, 
and  the  passage  of  bubbles  through  the  acid  has  ceased, 
break  oif  the  point  of  the  beak  at  A,  and  draw  a  consid- 
erable quantity  of  air  through  the  whole  apparatus  by 
applying  suction  at  the  mouth  of  the  bulbed  tube,  in  or- 
der to  carry  all  ammonia  remaining  in  the  combustion- 
tube  into  the  acid ;  disconnect  the  bulbed  tube  from  the 
other,  add  a  little  cochineal,  and  then  the  standard  sodic 
solution  until  the  acid  is  almost  neutralized,  empty  the 
contents  of  the  bulbs  into  a  beaker,  rinse  with  a  little 
water,  and  finish  the  titration  (§  45). 

For  each  cubic  centimetre  of  the  acid  that  was  neutral- 
ized by  the  ammonia  set  free,  the  substance  analyzed  con- 
tained 0.014  grm.  of  nitrogen. 

When  very  great  accuracy  is  required,  the  ammonia 
should  be  collected  in  hydrochloric  acid,  oily  matters  fil- 
tered out,  if  any  are  seen  in  the  acid  after  the  combustion 
6 


122  §    88.       BASES    AND    ACIDS   WITH    REAGENTS.  . 

is  finislied,  the  bulbs  rinsed  out  with  alcohol,  and  the  am- 
monia determined  with  the  aid  of  platinic  chloride  (§  47,  a). 
If  the  substance  is  very  rich  in  nitrogen,  it  must  be 
mixed  with  an  equal  quantity  of  j^ure  sugar,  in  order  to 
avoid  the  danger  of  an  impetuous  retrograde  current  in 
the  bulbed  tube,  when  the  evolution  of  gas  ceases  and 
the  whole  apparatus  is  filled  with  ammonia-gas. 

UREA.     CH4N0O.    60. 

86i  Urea  is  very  soluble  in  water  and  alcohol,  but  dif-' 
ficultly  soluble  in  ether. 

Reactions! — -When  heated  it  gives  off  ammonia. 

Nitric  or  oxalic  acid  causes  the  formation  of  a  white 
precipitate  in  concentrated  solutions  of  urea. 

Quantitative  estimation* — The  volumetric  method  of 
Liebig,  with  mercuric  nitrate,  is  easily  and  quickly  exe- 
cuted and  yields  accurate  results. 

To  prepare  the  standard  solution  of  mercuric  nitrate, 
heat  an  excess  of  mercury  with  concentrated  nitric  acid, 
concentrate  the  solution,  and,  on  cooling,  crystals  of  mer- 
curous  nitrate  will  be  deposited ;  pour  off  the  mother- 
liquor,  wash  the  crystals,  first  with  dilute  nitric  acid,  and 
then  with  cold  water,  dissolve  them  in  pure  nitric  acid, 
and  heat  the  sohition  until  a  drop  of  it  gives  no  precipi- 
tate or  turbidity  with  sodic  chloride  ;  evaporate  the  solu- 
tion on  the  water-bath  to  the  consistency  of  a  syrup,  dilute 
it  with  10  volumes  of  Avater,  let  it  stand  21:  hours,  and 
filter  if  any  precipitate  is  formed. 

To  determine  the  strength  of  this  solution,  dissolve 
10.864  grms.  of  pure,  ignited  sodic  chloride  in  1  litre  of 
water;  dilute  10  c.c.  of  the  mercuric  solution  with  90 
c.c.  of  water,  put  10  c.c.  of  this  diluted  solution  in  a  small 
beaker,  add  4  c.c.  of  a  cold  saturated  solution  of  sodic 
phosphate,  and  quickly,  before  the  precipitate  caused  by 
this  reagent  has  time  to  become  crystalline,  allow  the  so- 


§  86.     UKEA.  123 

lution  of  sodic  chloride  to  flow  in  from  a  burette  with 
constant  stirring,  until  the  precipitate  disappears,  and  the 
solution  becomes  clear  again.  Each  cubic  centimetre  of 
the  sodic  solution  required  corresponds  to  0.02  grm.  of 
mercuric  oxide ;  on  the  basis  of  this  determination,  then, 
the  amount  of  mercuric  salt  in  the  diluted  solution,  and 
the  strength  of  the  concentrated  solution,  can  be  estimated. 

Now,  to  bring  the  mercuric  solution  to  a  urea  standard, 
it  must  be  diluted  so  that  1  litre  will  contain  72  grms.  of 
mercuric  oxide ;  dilute  the  solution  almost  to  this  point, 
and  then  compare  it  with  a  solution  of  urea  of  known 
strength.  For  this  purpose,  dissolve  2  grms.  of  pure 
urea,  dried  at  100°  C,  in  water,  dilute  the  solution  to  100 
c.c.  and  put  15  c.c.  of  this  solution  in  a  beaker;  in  an- 
other small  beaker,  wash  a  few  crystals  of  sodic  bicar- 
bonate with  a  considerable  quantity  of  cold  water,  and, 
after  pouring  this  oif,  add  just  enough  water  to  make  a 
thin  paste  with  the  salt ;  have  ready  also  a  piece  of  clean 
glass,  with  its  under  surface  coated  with  asphaltum  varnish. 

Now,  allow  the  mercuric  solution  to  flow  slowly  from 
the  burette  into  the  solution  of  urea,  with  the  addition 
from  time  to  time  of  a  small  quantity  of  dry  sodic  car- 
bonate, in  order  to  nearly,  but  not  quite,  neutralize  the 
nitric  acid  that  is  set  free ;  the  solution  must  all  the  while 
have  a  slight  acid  reaction.  To  ascertain  whether  all  the 
urea  is  precipitated,  transfer  a  drop  of  the  solution,  on 
the  end  of  a  glass  rod,  to  the  glass  plate,  and  cover  it 
with  a  drop  of  the  paste  of  sodic  bicarbonate ;  if  no  yel- 
low color  appears  in  a  few  seconds,  wash  the  test-drop 
back  with  the  smallest  possible  quantity  of  water,  and, 
after  adding  a  little  more  mercuric  nitrate,  test  again  with 
the  sodic  bicarbonate ;  the  first  trace  of  a  yellow  color, 
that  appears  as  soon  as  the  two  drops  come  together,  in- 
dicates that  sufficient  mercuric  chloride  has  been  added. 

The  standard  mercuric  solution  is  to  be  diluted  so  that 
1  cubic  centimetre  corresponds  to  10  mgr.  of  urea,  or  to 


124  §    86.       BASES   AXD    ACIDS   WITH    REAGENTS. 

0.5  c.c.  of  this  solution  of  urea  of  known  strength  that 
has  been  prepared. 

M.  Byasson  ( Chemical  JVews  Amer.  Itepr.^  4,  143)  pre- 
pares this  standard  solution  by  dissolving  exactly  72 
grms.  of  pure  red  oxide  of  mercury,  or  mercuric  oxide,  in 
100  grms.  of  nitric  acid  diluted  with  half  its  weight  of 
water,  evaporates  the  solution  at  a  gentle  heat  until  acid 
vapors  appear,  and  then  makes  the  volume  up  to  one  litre 
at  15°  C;  if  the  dilution  causes  a  slight  turbidity,  a  few 
drops  of  nitric  acid  will  remove  it.  In  this  way,  he  states, 
a  solution  will  be  obtained  in  which  all  the  mercury  is 
present  as  mercuric  nitrate,  and  with  as  small  an  excess  of 
acid  as  possible  ;  while,  if  prepared  by  dissolving  mercury 
in  nitric  acid,  it  is  liable  to  contain  mercurous  nitrate. 

As  this  mercuric  solution  is  also  to  be  used,  in  anal- 
yses of  urine,  to  determine  the  sodic  chloride,  it  should 
also  be  titrated  with  reference  to  this.  Take  10  c.c.  of  a 
solution  of  sodic  chloride  containing  2"]^  of  the  salt  or  0.2 
grm.,  add  to  it  3  c.c.  of  the  standard  solution  of  urea, 
prepared  as  above,  and  5  c.c.  of  a  cold  saturated  solution 
of  pure  sodic  sulphate,  and  allow  the  mercuric  solution 
to  flow  from  the  burette  into  this  mixture  with  constant 
stirring,  until  there  is  a  permanent  turbidity  in  the  liquid ; 
the  amount  of  mercuric  solution  required  for  this  corres- 
ponds to  the  0.2  grm.  of  sodic  chloride ;  calculate  the 
amount  of  sodic  chloride  that  corresponds  to  1  c.c.  of  the 
standard  mercuric  solution,  and  mark  it  on  the  label  of 
the  bottle. 

For  the  determination  of  urea  in  a  solution  containing 
it  and  free  from  phosphoric  and  hippuric  acids,  proceed 
with  15  c.c,  as  directed  for  determining  the  standard  of 
the  solution  with  reference  to  urea,  after  having  first  de- 
termined the  sodic  chloride,  which  is  commonly  present, 
by  the  amount  of  the  standard  solution  required  to  pro- 
duce permanent  turbidity  ;  use  the  dry  sodic  carbonate  to 
maintain  the  neutrality  of  the  solution,  the  paste  of  the 


§    87.      FATTY    SUBSTANCES.  125 

bicarbonate  to  ascertain  the  point  of  saturation  with  mer- 
curic chloride,  and  so  on  in  the  manner  already  described. 

The  results  obtained,  however,  must  be  corrected  for 
very  dilute  or  very  concentrated  solutions  of  urea,  since 
the  standard  mercuric  solution  is  adapted  for  such  solu- 
tions only  as  contain  2°  |^  of  urea ;  if  the  solution  is  more 
concentrated  than  this,  the  yellow  color  appears  prema- 
turely ;  if  more  dilute,  it  does  not  appear  so  soon  as  it 
should. 

If  the  reaction  indicating  saturation  was  obtained  with 
10  c.c.  or  less  of  the  mercuric  solution,  subtract  the  prod- 
uct of  0.08  into  the  whole  number  of  cubic  centimetres  re- 
quired, from  this  total  quantity ;  if  the  reaction  was  obtain- 
ed with  less  than  15  c.c.  but  with  more  than  10  c.c,  subtract 
also,  in  addition  to  the  above  product,  the  product  of  0.06 
into  the  number  of  cubic  centimetres  required  above  10 ; 
if  more  than  15  c.c.  were  required,  but  less  than  20,  sub- 
tract also,  from  the  total  amount  used,  the  product  of  0.04 
into  the  number  of  cubic  centimetres  above  15,  in  addi- 
tion to  the  above  two  products.  (RcCutenherg,  Fres.  Zelt- 
schrift,  4,  500.)  The  final  remainder,  multiplied  into  0.01, 
will  give  tlie  amount  of  urea  in  the  15  c.c.  of  solution 
tested. 

In  case  the  solution  is  more  than  2"!  ^  strong,  then  more 
than  30  c.c.  of  the  standard  mercuric  solution  will  be  re- 
quired ;  for  each  cubic  centimetre  of  the  standard  solution 
used  above  30  c.c,  ^l^  c.c  of  water  must  be  added  to  the 
mixture,  before  taking  out  a  sample  dro^)  to  be  tested 
with  the  paste  of  sodic  carbonate. 

FATTY   SUBSTANCES. 

87i  Fats  are  insoluble  in  water,  somewhat  soluble  in 
strong  alcohol,  and  very  soluble  in  ether. 

Quantitatiye  estimation. — This  is  effected  by  heatmg 
the  finely  divided  substance  with  2-3  volumes  of  ether 


/ 
126  §    88.       BASES    AND    ACIDS    WITH    REAGEISTS. 

(Sp.  Gr.  rr  0.72),  evaporating  tlie  etherial  solution  of  fat  to 
dryness,  and  weighing  the  residue. 

Several  portions  of  ether  must  be  used,  and  the  extrac- 
tion is  best  conducted  in  a  flask  "^^ovided  witli  tubes  like 
a  washing-bottle,  and  which  is  connected  with  the  lower 
end  of  a  Liebig's  condenser  (§  36). 

The  extraction  may  not  be  considered  as  ended  until  a 
drop  of  the  last  filtrate  leaves  no  residue  when  evaporat- 
ed on  a  watch-glass.  The  solutions,  if  not  perfectly  clear 
as  they  came  from  the  filtering  flask,  should  be  filtered 
through  paper.  The  chlorophyll  in  the  green  parts  of 
plants  goes  into  solution  Avith  the  fat,  but  it  may  be  re- 
moved by  filtration  thi'ough  bone-black. 

The  clear  etherial  extracts  may  be  collected  in  a  gradu- 
ated cylinder,  and  the  fat  determined  in  an  aliquot  part  of 
the  well-mixed  liquid  by  evaporation  to  dryness,  drying 
the  residue  at  100°  C,  and  weighing. 

ALCOHOL.     CsTIeO.        46. 

88 •  Alcohol  is  miscible  with  water  in  all  proportions. 

QuantitatiYC  estimation. — This  is  eflfected  by  distilling 
the  alcohol  ofi",  and  estimating  it  in  the  distillate  by  the 
specific  gravity. 

a.  To  10  c.c.  of  the  solution  to  be  examined,  which 
must  contain  no  free  A'^olatile  acid,  as  acetic,  for  example, 
add  its  volume  of  water,  and  subject  the  whole  to  distill- 
ation in  a  small  flask  connected  with  a  small  Liebig's 
condenser.  Collect  the  distillate  in  a  specific-gravity  bot- 
tle with  a  mark  on  it,  indicating  a  capacity  of  10  c.c. 
When  somewhat  less  ^  than  half  the  liquid  has  been  dis- 
tilled over,  remove  the  specific-gravity  bottle  from  the 
tube  of  the  condenser,  bring  the  temperature  of  the  dis- 
tillate to  15°  C.,fill  up  to  the  mark  with  water,  and  weigh. 
Knowing  the  weight  of  10  c.c.  of  water  at  this  tempera- 


§    88.       ALCOHOL.  127 

ture  (weight  of  1  cubic  centimetre  =  0.999183  grm.),  we 
can  calculate  the  specific  gravity  of  this  distillate,  that 
contains  all  the  alcohol  that  was  in  the  liquid  examined, 
and  from  Table  Y,  learn  the  per  cent  of  alcohol  in  the 
distillate.  Then  the  per  cent  of  alcohol  by  weight  in  the 
solution  examined  is  readily  calculated  if  the  weight  of 
10  c.c.  of  that  solution  is  known. 

Griffin,  in  his  examination  of  wines  {J.  J'.  Griffin, 
Gheinical  Testing  of  Wines  and  /Spirits),  used  25  c.c. 
of  the  alcoholic  liquid,  added  its  volume  of  water  to  it, 
made  the  volume  of  the  distillate  up  to  50  c.c,  and  deter- 
mined its  specific  gravity. 

If  the  substance  to  be  examined  contains  free  acetic 
acid,  add  a  little  soda  to  the  liquid  before  distillation. 
The  distillate  should  have  no  acid  reaction. 

b.  The  alcohol  in  a  wine  may  be  approximately  esti- 
mated by  evaporating  a  measured  quantity  to  about  half 
its  bulk,  adding  water  until  the  original  volume  is  re- 
stored, and  determining  the  specific  gravity  of  this  liquid; 
then  subtract  the  number  by  which  this  specific  gravity 
is  greater  than  one,  from  the  specific  gravity  of  the  alco- 
holic liquid  itself,  and  take  the  remainder  as  the  specific 
gravity  of  the  mixture  of  alcohol  and  water  in  that  liquid, 
and  get  the  per  cent  of  alcohol  corresponding  to  this 
specific  gravity  from  Table  V.  To  illustrate  the  principle, 
suppose  a  wine  is  examined  whose  specific  gravity  equals 
0.9951 ;  after  evaporation  down  to  one-half,  and  adding 
water  until  the  original  volume  is  restored,  the  specific 
gravity  is  1.0089. 

0.9951  —  0.0082  =  0.9869. 

Against  the  specific  gravity  of  0.9862  in  the  table,  the 
per  cent  of  alcohol  is  found  to  be  8. 


128  §    89.       SPECIAL    METHODS    OF    ANALYSIS. 

CHAPTER  lY. 

Special  Methods  of  Analysis. 
1. 

COURSE  OF  QUALITATIVE  ANALYSIS. 

89.  The  following  course  of  analysis  is  designed  as 
a  general  guide  in  qualitative  analytical  work.  Only  a 
single  reaction  for  each  substance  is  mentioned  in  it,  and 
that  is  generally  the  most  delicate  one ;  for  fuller  de- 
tails in  regard  to  this  particular  reaction,  and  for  a  few 
other  ones  that  may  in  some  cases  be  applied  as  confirma- 
tory tests,  the  student  is  referred  to  Chapter  III. 

He  should,  before  undertaking  to  work  with  the  aid  of 
this  course,  thoroughly  familiarize  himself,  by  actual  ob- 
servation, with  the  behavior  of  the  different  acids  and 
bases  with  reagents,  so  that  he  may  know  what  is  indi- 
cated by  any  particular  reaction,  the  moment  he  sees  it. 

The  mode  of  working  with  the  aid  of  the  scheme  given 
below  is  best  explained  by  an  example.  Suppose  we  have 
a  solid  containing  CI,  P20^,  SO3,  K,Fe,  and  Mn.  Begin- 
ning with  1  in  the  left-hand  column  of  figures,  in  the  course 
for  the  detection  of  the  acids,  the  first  question  is, 
whether  the  substance  is  a  soJid  or  a  solution.  It  being 
the  former,  we  are  referred,  in  the  right-hand  column  of 
figures  to  2 ;  going  then  to  2,  in  the  left-hand  column, 
we  find  that  the  solubility  of  the  substance  is  to  be  test- 
ed ;  we  apply  the  solvents  in  the  order  there  indicated, 
and  find  that  it  is  soluble  in  dilute  nitric  acid,  when  wo 
are  referred  to  G ;  going  to  6,  in  the  left-hand  column,  we 
get  no  gritty  residue  on  evaporation  to  dryness,  and  there- 
fore no  silicic  acid  is  present ;  passing  on  to  7,  to  which 
we  are  referred  next,  we  get  no  such  reaction  as  is  de- 


§    89.       COUKSH    OF    QUALITATIVJa    ANALYSIS.  129 

scribed  there,  nor  such  ns  in  0 ;  therefore,  carbonic  acid 
and  sulphur  are  absent ;  we  do  get,  however,  the  fine 
white  precipitate  as  described  in  9,  and  note  sulphuric 
acid  as  present;  we  also  get  a  yellow  precipitate  in  10, 
and  make  a  note  of  phosphoric  acid  as  present ;  we  do 
not  get  the  reaction  in  11,  but  get  a  white  precipitate  in 
12,  the  formation  of  which,  under  the  circumstances,  indi- 
cates that  cyanogen,  iodine,  ferrocyanogen,  or  chlorine, 
may  be  present ;  a  precipitate  would  be  given  also  by 
sulphur,  if  that  were  present,  but  the  test  for  this  element 
has  already  been  made ;  we  do  not  find  the  first  three 
substances  named  above,  and  learn  in  16  that,  consequent- 
ly, chlorine  is  present ;  we  find  no  nitric  acid  in  17,  and, 
as  the  substance  is  not  blackened  when  heated  as  directed 
in  I85  no  organic  acids  are  present,  and  wo  have  finished 
the  examination  for  the  acids. 

Passing  to  the  detection  of  the  bases,  we  have  the 
question  in  1  already  answered  for  us,  with  this  small 
difierence,  that,  in  the  examination  for  the  bases,  a  hydro- 
chloric-acid solution  is  preferable  to  a  nitric-acid  solution  ; 
going  on  to  3,  we  add  sulphuric  acid,  and  get  no  reaction, 
even  after  the  mixture  of  substance  and  reagent  has  stood 
some  time ;  no  lead  or  barium,  and,  at  the  most,  only 
traces  of  calcium,  can  be  present ;  passing  on  to  7  we  find 
no  ammonium;  we  get  the  violet  color,  indicating  potas- 
sium, in  9,  after  having  properly  prepared  the  solution  as 
directed  in  8 ;  and  so  working  on,  we  find  no  copper  in 
10,  but  do  get  iron  in  11,  and  manganese  in  15,  and  after 
that,  nothing  more  before  reaching  the  end  of  the  course. 

It  will  be  noticed  that  sulphuretted  hydrogen  and  am- 
monic  sulphide,  and  also  the  blowpipe,  are  used  but  little 
or  not  at  all  in  this  course  of  analysis ;  there  are  suffi- 
ciently good  reasons  why  their  use  should  be  dispensed 
with,  if  it  can  be  done  without  impairing  the  reliability 
of  the  work. 

The  plan  of  the  course  for  the  bases  corresponds  in  the 
6* 


130  SPECIAIi   METHODS    OF   ANALYSIS. 

main  witli  that  of  Zettnow.     {Poggeyidorf^s  Annalen^ 
103,  324.) 

The  attention  of  the  analyst  is  called  to  Table  X, 
where  the  average  and  extreme  composition  of  agricul- 
tural materials  and  products  are  given ;  by  consulting 
this  table  he  can  ascertain  what  he  may  expect  to  find  in 
any  substance  under  examination,  that  is  used  in,  or 
produced  by,  agriculture,  and  whether  or  not  he  must 
needs  work  with  special  care,  or  with  large  quantities  of 
the  substance,  in  order  that  a  small  quantity  or  traces  of, 
any  element  or  compound  shall  not  escape  detection. 

A, 

DETECTION  OF  ACID  ELEMENTS  AND  ACIDS. 

1.  a.  The  substance  is  a  solution ;   this  solution  will 
be  referred  to  as  th.Q  first  solution,      -     -     .     .         6 
h.  Not  a  solution.      -  -         -         -        -        -      2 

2.  a.  The  substance  is  soluble  in  water,  or  in  dilute 
or  concentrated  nitric  or  hydrochloric  acid ;  this 
solution  will  be  referred  to  as  the^rs^  solutlo7i.  -  6 
h.  It  is  partially  soluble  in  water  or  acids,  as  indi- 
cated by  the  residue  left  undissolved  even  after 
heating,  and  by  the  distinct  residue  left  on  evapo- 
ration of  a  drop  of  the  solvent  with  which  the 
substance  has  been  treated.    Treat  a  larger  portion 

of  the  finely  divided  substance  with  another  por- 
tion of  the  solvent,  filter,  and  mark  the  filtrate  F  2. 
With  the  contents  of  the  filter  go  to     -     -     -     -     3 
c.  It  is  quite  insoluble  in  water  or  acids.     -     -     -     3 

3.  A  portion  of  the  insoluble  substance,  in  the  shape 
of  a  very  small  fragment,  if  possible,  rather  than 
a  fine  powder,  is  fused  for  a  considerable  time  in  a 
bead  of  phosphorus-salt  on   platinum  wire ;   the 


DETECTIOX    OF    ACIDS.  131 

fragment  is  not  entirely  dissolved,  but  remains 
visible  in  the  bead,  retaining  its  original  form. 
Also,  Avhen  the  substance  in  powder  is  fused  in  a 
bead  of  sodio  carbonate  on  the  platinum  wire,  the 
bead  froths,  carbonic  acid  being  set  free.  Both 
these  reactions  together  indicate  Silicic.     -     -     -    4 

4.  A  small  portion  of  the  original  substance,  finely- 
pulverized,  is  made  into  a  paste  with  concentrated 
sulphuric  acid  in  a  leaden  tray,  the  tray  is  covered 
with  a  piece  of  Bohemian  glass  coated  with  wax, 
and  from  which  the  coating  has  been  removed  in 
a  few  places  with  a  sharp-pointed  instrument,  and 
the  whole  is  gently  heated  for  about  a  half  an 
hour.  The  glass  is  found  to  be  corroded  where 
the  wax  was  removed  (see  §  68).     Fluorine.      -      5 

5.  The  insoluble  substance  has  black  particles  in  it, 
that  are  entirely  or  partially  consumed  when  heat- 
ed on  platinum  foil.     (Coal.)     Carbox.      .     -      -     6 

6.  Evaporate  a  portion  of  the  first  solution  or  of  F  2 
to  dryness,  after  adding  hydrochloric  acid,  if  not 
already  present,  ignite  the  residue  gently,  moisten 
it  with  concentrated  hydrochloric  acid,  let  stand  a 
short  time,  add  considerable  water,  and  digest  the 
mixture.  A  white  poAvder,  or  perhaps  a  reddish 
one  if  much  iron  is  present,  remains  undissolved, 
that  feels  gritty  under  the  glass  rod.  Soluble 
Silicic. -       1 

7.  The  addition  of  dilute  sulphuric  acid  to  a  small 
quantity  of  the  original  substance  causes  efferves- 
cence, that  accompanies  the  evolution  of  a  colorless 
gas ;  a  drop  of  lime-water,  suspended  on  the  end 
of  a  glass  rod,  and  held  above  the  liquid  in  the 
test-tube,  is  made  turbid.     Carbonic.    -     -     -     -    ^ 

6.  In  the  same  experiment  a  colorless  gas  is  evolved, 
havini^  an  offensive  odor,  and  blackening  a  piece  of 


132  SPECIAL    METHODS    OF    ANALYSIS. 

moistened  lead-paper  that  is  lield  in  the  mouth  of 
the  tube.     {Uydrosulphurlc.)     Sulpiiue.     -     -     .      9 
9.  The  first  sohition,  or  F  2,  after  acidification  with 
hydrochloric  acid,  if  not  ah-eady  acid,  gives  a  white, 
finely  pulverulent  precipitate  with  baric  chloride. 

SULPHUKIC.  - -10 

Sulphuric  acid  may  be  found  also  in  the  insoluble 
substance  in  the  course  of  the  examination  for 
bases. 

10.  If  a  very  small  quantity  of  the  solution  of  the  sub- 
stance is  added  to  ammonic  molybdate,  a  pale  yel- 
low precipitate  is  formed,  at  once,  or  after  some  time, 
a  part  of  which  adheres  strongly  to  the  sides  of 
the  tube ;  the  precipitate  is  soluble  in  ammonia. 
Phosphoeic. 11 

11.  To  a  portion  of  the  hot  solution,  containing  a 
slight  excess  of  acid,  add  about  twice  its  volume 
of  alcohol,  and  then  dilute  sulphuric  acid  or  am- 
monic sulphate,  and  filter  if  any  precipitate  is 
formed,  heat  the  filtrate  until  the  alcohol  is  ex- 
pelled, add  ammonia  in  slight  excess,  and  then 
acetic  acid  until  the  ammonia  is  more  than  neutral- 
ized, and  finally  calcic  sulphate.  A  fine  white  pre- 
cipitate appears,  at  once,  or  after  some  time. 
Oxalic. 12 

12.  To  a  small  portion  of  the  dilute  nitric  acid  solu- 
tion of  the  substance,  or  of  the  aqueous  solution 
acidified  with  nitric  acid,  add  argentic  nitrate. 

a.  No  precipitate  is  formed.  (Traces  of  cyano- 
gen or  iodine  may  perhaps  be  found  by  applying 

the  tests  in  12  5,  and  13.) IT 

h.  A  precipitate  is  formed. 

Treat  a  small  portion  of  the  original  substance 
with  a  little  dilute  sulphuric  acid,  in  a  watch-glass, 
and    quickly  invert    another  watch-glass,  with  a 


DETECTION    OF    ACIDS.  133 

drop  of  amnionic  sulphide,  saturated  with  sulphur, 
in  its  centre,  over  the  first  one ;  after  a  few  min- 
utes evaporate  this  drop  of  ammonic  sulphide  to 
dryness  with  a  gentle  heat,  and  moisten  the  dry- 
residue  with  ferric  chloride.  A  deep  red  color 
appears.     Cyanogen-. 13 

13.  To  a  portion  of  the  aqueous  solution  or  extract  of 
the  substance,  add  two  or  three  drops  of  potassic 
dichromatc,  or  enough  to  give  a  pale  yellow  color 
to  the  liquid,  and  then  a  few  drops  of  concentrat- 
ed hydrochloric  acid.  A  drop  of  this  mixture  on 
starch-paper  colors  it  blue.     Iodine.     -     -     -     -    14 

14.  A  portion  of  the  first  solution  gives,  w^ith  ferric 
chloride,  a  deep  blue  precipitate,  unaffected  by  di- 
lute acids,  but  decomposed  by  sodic  hydrate  with 
the  conversion  of  the  blue  color  into  a  reddish 
one.     Ferkocyanogen. 15 

15.  a.     1^0  very  decided  reaction  was  obtahied  in  12 

for  cyanogen. 16 

h.  A  decided  reaction  was  obtained  for  cyanogen. 
To  the  dilute  nitric  acid  extract  of  the  substance, 

or  the  aqueous  extract  acidified  with  nitric  acid, 
add  argentic  nitrate  as  long  as  a  precipitate  is 
formed,  filter,  -wash  the  precipitate  a  little,  dry  it, 
and  ignite  it  gently  in  a  porcelain  crucible  until  it 
is  fused,  pour  a  little  water  and  a  few  drops  of  di- 
lute sulphuric  acid  over  the  fused  mass  after  it  is 
cool,  put  a  piece  of  zinc  in  contact  with  it,  and  let 
the  whole  stand  some  time ;  finally  filter,  acidify 
the  filtrate  with  nitric  acid,  and  add  argentic  ni- 
trate. 

a.  No  precipitate. -     17 

1).  A  white  precipitate  is  formed ;  no  iodine  or 
ferrocyanogen  has  been  found.     Chlorine.  -   -    IT 
c.  A  precipitate  is  formed,  but  it  is  not  w^bite, 


134  SPECIAL    METHODS    OF    ANALYSIS. 

or  iodine  or  ferrocyanogen  lias  been  found.  -    -    16 

10.  a.  The  precipitate  in  12  was  white,  and  no  cyano- 
gen, iodine,  or    ferrocyanogen,  has    been  found. 

Chlorine. 17 

h.  Not  Avhite,  or  one  or  more  of  these  substances 
was  found  ;  treaVthe  precipitate  obtained  in  15,  or, 
if  cyanogen  was  absent,  that  obtained  in  12,  with 
amnionic  hydrate,  filter,  and  add  dilute  nitric  acid 
to  the  filtrate  until  acid  reaction.  A  white  pre- 
cipitate appears,  which,  if  abundant,  collects  in 
curdy  flakes  on  agitating  the  mixture.     Chloeixe.  17 

17.  Treat  a  portion  of  the  original  substance  with  a 
little  dilute  sulphuric  acid  if  it  is  a  solid,  or  with 
concentrated  acid  if  it  is  a  solution,  add  copper 
turnings,  and  heat  the  mixture.  Red  fumes  are 
evolved,  which  may  be  more  readily  perceived  on 
holding  the  tube  over  white  paper,  and  looking 
through  it  lengthwise.     Nitric.         -         -         -        18 

18.  a.  A  portion  of  the  solid  substance,  when  quickly 
heated  to  a  high  temperature  on  platinum  foil,  is 
blackened,  with  separation  of  carbon,  and  an  odor 

of  burning  organic  matter  is  given  off.         -         -     19 

h.  Not  blackened.  Absence  of  acetic,  tartaric, 
and  other  organic  acids.     Finis.       -        -         -       -  B. 

19.  A  portion  of  the  solid  or  solution  gives  acetic 
ether  when  heated  with  concentrated  sulphuric 
acid  and  alcohol ;  the  pleasant  aromatic  odor  of 
this  ether  may  be  most  readily  distinguished  from 
that  of  common  ether,  Avhich  is  formed  at  the 
same  time,  after  the  liquid  has  become  quite  cold. 
Acetic.        -        - 20 

20.  To  a  portion  of  the  first  solution,  tliat  must  be  tol- 
erably concentrated,  add  ammonia  until  it  is  faint- 
ly alkaline,  filter  if  not  clear,  add  a  little  amnionic 


DETECTION    OF    ACIDS.  135 

chloride,  then  calcic  chloride,  agitate  tlie  mixture 

vigorously,  and  let  it  stand  10-20  minutes. 

a.  No  precipitate  is  formed.         -         -        -         -     21 

h.  A  white  precipitate  is  formed ;  filter,  and  mark 
the  filtrate  F.  20.  Digest  the  precipitate  in  the 
cold,  with  sodic  hydrate,  with  frequent  agitation, 
dilute,  filter,  and  boil  the  filtrate.  A  white  gelat- 
inous precipitate  is  formed  ;  test  it  with  ammonia 
and  argentic  nitrate  (§  71).     Taetaeic.       -      -      21 

21.  To  F.  20,  or  to  the  clear  mixture  of  original  solu- 
tion and  calcic  chloride  obtained  in  20,  add  consid- 
erable alcohol. 

a.  No  precipitate.  Finis.  -  -  -  -  B. 
h.  A  white  precipitate  is  fonnecl ;  filter,  wash  the 
precipitate  with  a  little  alcohol,  dissolve  it  in  a 
small  quantity  of  dilute  hydrochloric  acid,  add  am- 
monia in  slight  excess,  and  boil  the  liquid  some 
time. 

aa.  No  precipitate. 22 

hh.  A  white  precipitate  is  formed  ;  filter  the  liquid 
while  boiling  hot,  and  mark  the  filtrate  F.  21.  Dis- 
solve the  precipitate  on  the  filter  in  a  very  little 
dilute  hydrochloric  acid,  add  ammonia  in  slight 
excess,  and  boil  this  mixture.  A  similar  white 
precipitate  is  formed  again.     Citkic.       -      -      -    22 

22.  F.  21,  or  the  solution  obtained  in  21  that  gave  no 
precipitate  on  boiling,  may  contain  malic  acid. 
Add  considerable  alcohol  to  it. 

a.  No  precipitate  is  formed.  Finis.  -  -  ^' 
h.  A  white  precipitate  is  formed.  Probably  Malic. 
To  be  sure,  treat  the  precipitate  with  acetic  acid, 
add  alcohol,  filter  the  liquid  if  not  clear,  add  plum- 
bic acetate  to  the  filtrate,  and  ammonia  until  the 
liquid  is  neutral,  filter  out  the  precipitate,  wash  it, 


136  SPECIAL    METHODS    OF    ANALYSIS. 

suspend  it  in  water  through  wliich  a  current  of 
sulphuretted  hydrogen  is  passed,  filter,  evaporate 
the  filtrate  to  dryness  on  the  water-bath,  and  heat 
the  residue,  supposed  to  be  malic  acid ;  maleic 
acid  should  be  formed  (§  73).       -        -        -      -      B. 

B. 

DETECTION  OF  THE  BASIC  ELEMENTS. 

1.  a.  The  substance  is  a  solution,  or  it  is  soluble  in 
water,  or  dilute  or  concentrated  hydrochloric  or 
nitric  acid.     This  solution  will  be  referred  to  as 

the^r^^  solution. 3 

b.  Not  soluble,  or  only  partially  soluble ;  separate 
the  soluble  from  the  insoluble  part  by  filtration  ; 
this  filtrate  will  be  referred  to  as  the  Jlrst  solution.     2 

2.  This  insoluble  substance  was  found,  in  the  exami- 
nation for  acids,  to  consist  entirely  of  carbon.      -      3 
Not.     Dry  it,  mix  it  intimately  with  four  parts  of 

•  potassic  and  sodic  carbonate,  and  a  little  sodic  ni- 
trate, fuse  the  mixture  10-20  minutes  on  platinum 
foil,  and  exhaust  the  fused  mass  with  hot  water ; 
decant  off  this  aqueous  extract,  wash  the  residue 
once  or  twice  by  decantation,  then  treat  it  with 
very  dilate  hydrochloric  acid,  and  evaporate  the 
mixture  to  dryness ;  moisten  this  second  residue 
with  concentrated  hydrochloric  acid,  and,  after  a 
while,  add  water,  heat,  and  finally  separate  this 
acid  solution  from  the  insoluble  silica,  by  filtra- 
tion. 

Acidify  the  aqueous  extract  of  the  fused  mass,  ob- 
tained above,  with  hydrochloric  acid,  and  test  a 
small  portion  of  it  for  sulphuric  acid  with  baric 
chloride  ;  if  a  fine  white  precipitate  is  formed,  and 
lead  or  barium  is  subsequently  found  among  the 


DETECTION    OF   THE    BASIC   ELEMENTS.  137 

basic  elements,  the  insoluble  substance  was  com- 
posed, at  least  in  part,  of  plumbic  or  baric  sul- 
phate ;  if  lead  or  barium  is  not  found,  but  calcium 
is,  then  the  insoluble  substance  consisted,  at  least 
partly,  of  calcic  sulphate,  which  requires  considera- 
ble water  or  dilute  acid  for  its  complete  solution ; 
if  no  sulphuric  acid  is  found,  the  insoluble  sub- 
stance contained  only  silica  or  silicates,  besides, 
possibly,  a  fluoride  and  carbon. 

Mix  the  acid  solution,  filtered  from  the  silica  as 
above,  and  the  remainder  of  the  aqueous  extract 
together,  and  without  filtering  out  any  precipitate 
that  may  be  formed,  proceed  with  the  analysis  as 
in  3,  if  it  is  desired  to  analyze  this  solution  sepa- 
rately, in  order  to  ascertain  the  composition  of  the 
insoluble  part  of  the  substance  ;  but  it  will  not  be 
found,  in  any  case,  to  contain  arsenic  or  ammoni- 
.  um,  nor  will  copper  or  zinc  be  likely  to  be  found 
in  it,  and  not  in  any  case  unless  it  contained  silica  • 
lead  and  barium  may  be  present  as  sulphates,  and 
the  latter  possibly  as  a  silicate. 
Potassium  and  sodium  cannot,  of  course,  be  tested 
for  in  this  solution  ;  if  it  is  desired  to  examine  the 
insoluble  substance  with  respect  to  the  presence  of 
these  metals,  the  silicate  must  be  attacked  with 
hydrofluoric  acid  or  a  fluoride,  in  the  manner  di- 
rected for  the  quantitative  analysis  of  silicates. 
(§  58,  c.) 

If  it  is  not  necessary  to  analyze  this  solution  sepa- 
rately, it  may  be  mixed  at  once  with  the  Jirst  solu- 
tion^ reserving,  however,  a  portion  of  this  latter 
for  the  examination  for  the  alkaline  metals.  -  -  3 
3.  Heat  a  portion  of  the  nearly  neutral,  first  solution 
to  boiling,  add  to  it  about  its  volume  of  alcohol, 
or  twice  its  volume  if  the  solution  is  very  dilute, 


188  SPECIAL   METHODS    OF   ANALYSIS. 

and  then  add  dilute  sulphuric  acid  as  long  as  a  pre- 
cij^itate  is  formed. 

a.  No  j)recipitate  is  formed,  even  after  vigorous 
agitation  and  some  time ;  expel  the  alcohol  from 
the  liquid  by  boiling  it  a  few  minutes,  and  mark  it 

F.  3. 

h.  A  white  precipitate  is  formed ;  let  the  mixture 
stand  awhile,  filter  the  liquid  while  hot,  boil  the 
filtrate  a  few  minutes  to  expel  the  alcohol,  and 
mark  it  F.  3.         -        -  .... 

4.  Agitate  the  precipitate  obtained  in  3  vigorously 
with  considerable  water,  filter,  and  add  amnionic 
oxalate  to  the  clear  filtrate.  A  white  precipitate 
indicates  Calcium.  .  .         _         .        - 

5.  Treat  the  contents  of  the  filter  in  4  with  ammonic 
tartrate,  heat  gently,  filter,  acidify  the  titrate 
with  acetic  acid,  and  add  a  little  potassic  dichro- 
mate.     A  yellow  precipitate  indicates  Lead. 

6.  Wash  the  residue  on  the  filter  in  5  well,  boil  it 
about  10  minutes  with  8-10  times  its  bulk  of  sodic 
carbonate,  add  water,  filter,  wash  the  contents  of 
the  filter  very  carefully,  pour  a  little  dilute  hydro- 
chloric acid  over  this  residue,  and  add  calcic  sul- 
phate to  the  solution  that  passes  through.  A  fine 
white  precipitate,  or  a  turbidity,  indicates  Barium. 

7.  Put  about  a  third  of  F.  3,  or  a  corresponding 
amount  of  the  first  solution,  into  a  small  flask,  add 
baric  hydrate  as  long  as  it  gives  a  precipitate,  and 
then  a  little  more,  so  as  to  be  sure  of  an  excess, 
heat  the  mixture,  and  hold  a  piece  of  nioistened 
red  litmus-paper  or  yellow  turmeric-pnper  in  the 
tube.  The  paper  is  colored  blue  or  brown.  Am- 
monium.          

8.  Heat  the  mixture  in  7  until  all  or  nearly  all  the 
ammonia  is  expelled,  filter,  add  a  little  baric  hy- 


DETECTION    OF   THE    BASIC    ELEMENTS.  139 

drate  to  the  filtrate,  to  bo  sure  that  no  further  pre- 
cipitation will  be  produced,  then  add  ammonic 
carbonate  as  long  as  a  precipitate  is  formed,  avoid- 
ing, however,  a  great  excess  of  the  reagent,  heat 
and  filter,  and  evaporate  the  filtrate  nearly  to 
dryness. 

A  drop  of  this  filtrate,  evaporated  to  dryness  in 
the  platinum  wire  loop,  gives  a  yellow  color  to  the 
flame  of  a  Bunsen's  gas-burner.     Sodium.     -    -    -    9 

9.  "in  a  similar  experiment  the  flame  is  violet,  or  vio- 
let-red when  seen  through  blue  glass.    Potassium.  10 

10.  To  a  small  portion  of  F.  3,  add  ammonia  very 
carefully  until  the  free  acid  is  just  neutralized,  and 
then  a  little  ammonic  sulphide,  drop  by  drop,  with 
constant  agitation,  and  heat  the  mixture. 

a.  No  precipitate  is  formed  at  any  time.     (Traces      v 
of  copper,  arsenic,  iron,  and  manganese,  may  per- 
haps be  found  by  applying  the  tests  described  in 
10  b,  12,  14,  and  15  ^»). 18 

h.  A  precipitate  is  formed. 

To  a  small  portion  of  F.  3,  add  ammonia  until  the 
well-mixed  liquid  smells  strongly  of  the  reagent, 
and  let  the  precipitate  settle  if  any  is  formed.  The 
clear  supernatant  liquid  is  blue.     Copper.       -      -  11 

11.  In  the  same  experiment  a  red  flocculent  precipi- 
tate is  obtained,  the  color  of  which  may,  however, 
not  appear,  in  case  much  copper  is  present,  until  it 
has  been  collected  on  a  filter  and  washed  a  few 
times.     Ieon. 1^ 

12.  If  copper  has  been  found  in  notable  quantity,  put 
the  remainder  of  F.  3  in  a  small  flask,  add  two 
or  three  pieces  of  pure  zinc,  and  close  the  flask 
with  a  perforated  cork,  in  which  is  a  glass  tube 
drawn  out  to  a  fine  jet. 


140  SPECIAL    METHODS    OF   ANALYSIS. 

If  copper  was  not  found,  take  only  a  small  part  of 
F.  3  for  this  trial. 

Care  must  be  taken  not  to  inhale  the  gas  from  the 
flask,  if  there  is  any  reason  to  suspect  that  arsenic 
is  present. 

After  the  hydrogen  has  been  evolved  a  few  min- 
utes, wrap  a  towel  around  the  flask,  ignite  the  jet 
of  gas,  and  hold  a  cold  porcelain  surface  in  the 
flame.  Black  lustrous  spots  are  deposited  on  the 
porcelain  surface  where  the  flame  comes  in  contact 
with  it.     Aksenic. 13 

13.  a.  Copper  was  not  found,  and  only  a  small  portion 

of  F.  3  was  taken  for  the  test  in  12.  -  -  -  14 
h.  Copper  was  found,  and  a, large  portion  of  F.  3 
is  under  examination.  Allow  the  action  of  the 
zinc  to  continue  10-15  minutes,  or  until  all  the  cop- 
per is  precipitated ;  a  much  longer  time  may  be  re- 
quired if  the  solution  contains  a  notable  quantity 
of  nitric  acid  ;  finally  filter  the  liquid  from  the  pre- 
cipitated metal,  and  mark  the  filtrate  F.  13.     -     -    14 

14.  Add  a  little  nitric  acid  to  a  portion  of  F.  13,  or  of 
F.  3,  if  there  is  no  F.  13  and  the  first  solution  did 
not  already  contain  free  nitric  acid  in  excess,  and 
heat  the  mixture  to  boiling. 

a.  An  unmistakable  reaction  for  iron  was  obtained 

in  11. 15 

h.  Not.  To  a  small  portion  of  this  solution  add 
potassic  sulphocyanate.  A  deep  red  color  appears. 
Iron.         -..-_-•.-        15 

15.  To  a  large  portion  of  the  solution  obtained  in  14, 
add  amnionic  carbonate  in  excess. 

a.  The  precipitate  which  may  have  been  formed 
at  first  is  entirely  re-dissolted  by  the  excess  of  the 
reagent,  and  the  solution  remains  quite  clear,  even 
after  a  hot  digestion  of  12  hours.         -        -        -      17 


DETECTION    OF   THE   BASIC   ELEMENTS.  141 

h.  Not.  Filter  the  precipitate  out,  wash  it  with 
hot  w^ater,  dry  a  large  portion  of  it,  and  mix  it  in- 
timately with  three  or  four  times  its  bulk  of  a  mix- 
ture of  equal  parts  of  potassic  and  sodic  carbon- 
ate, and  of  potassic  or  sodic  nitrate,  and  fuse  the 
mixture  well  on  platinum  foil.  The  fused  mass  is 
bluish  green.     Manganese. 

If  the  substance  contains  little  or  no  copper  or 
iron,  this  reaction  for  manganese  may  sometimes 
be  obtained  with  the  original  substance,  when  not 
obtained  here  (§53). 16 

10.  Boil  the  fused  mass  on  the  platinum  foil  with  two 
or  three  cubic  centimetres  of  water,  until  it  is  loos- 
ened from  the  foil,  filter,  add  dilute  nitric  acid  to 
the  filtrate,  drop  by  drop,  as  long  as  any  efferves- 
cence is  produced,  and  then  add  ammonia  very 
slowly  and  carefully,  until,  after  stirring  well,  the 
liquid  has  a  faint  alkaline  reaction  ;  heat  the  mix- 
ture a  few  minutes,  and  let  it  stand  a  long  time  in 
a  warm  place,  if  no  j^recipitate  appears  at  first.  A 
white  flocculent  precipitate  is  formed,  at  once,  or 
after  some  time.     Aluminium.  -        -         -         17 

17.  To  another  portion  of  the  first  solution  add  sodic 
hydrate  in  excess,  boil,  and  filter ;  to  the  filtrate 
add  a  few  drops  of  ammonic  carbonate,  and  then 
ammonic  chloride  in  excess,  boil  the  mixture  as 
long  as  any  odor  of  ammonia  is  given  off,  and  a 
portion  of  the  filtered  liquid  gives  no  further  pre- 
cipitate on  being  boiled  still  more ;  filter  the 
whole,  and  add  potassic  ferrocyanide  to  the  filtrate. 

A  white  precipitate  or  a  turbidity  appears.     Zinc.  18 

18.  a.  The  substance  contains  no  phosphoric  acid,  or 

only  traces  of  it. 19 

b.  It  does  contain  a  notable  quantity  of  this  acid. 
Add  ferric  chloride  to  another  portion  of  F.  13,  or 


142  SPECIAL   METHODS    OF    ANALYSIS. 

to  a  corresponding  quantity  of  F.  3,  if  there  is  no 
F.  13,  until  a  drop  of  the  mixture  gives  a  reddish 
precipitate  with  ammonia.         -         -         -         -         19 

19.  To  the  solution  to  which  Fe^Cl^  has  been  added 
(18),  or  to  the  remainder  of  the  filtrate  F.  13,  if 
no  P2O5  was  present  in  the  substance,  or  to  a  cor- 
responding quantity  of  F.  3,  if  there  is  no  F.  13, 
add  ammonic  carbonate  until  a  slight  permanent 
precipitate  remains  after  vigorous  stirring ;  if  no 
precipitate  appears,  the  reagent  may  be  added  un- 
til it  is  in  slight  excess,  and  the  solution  is  faintly 
alkaline. 

a.  No  ferric  salt  has  been  added  to  the  solution, 
and  it  remains  quite  clear,  or  only  a  fine  white  pre- 
cipitate is  formed  after  boiling  it.  -  -  -  20 
h.  AJlocculent  precipitate  is  formed  ;  heat  the  so- 
lution to  boiling,  add  a  boiling  solution  of  sodic 
acetate  as  long  as  a  precipitate  is  formed,  and  fil- 
ter the  hot  liquid  immediately  ;  mark  this  filtrate 
F.  19. -       2a 

20.  a.  Calcium  has  been  found.  -  -  -  -  21 
h.  Not.  To  test  for  traces  of  the  metal,  add  am- 
monic sulphide  to  the  filtrate  from  the  precipitate 
by  sodic  acetate,  or,  if  this  precipitation  was  not 
found  to  be  necessary  in  19,  to  the  liquid  contain- 
ing ammonic  carbonate  in  slight  excess,  after  acidi- 
fication with  acetic  acid  if  not  clear,  filter  out  any 
precipitate  that  may  be  formed,  and  add  ammonic 
chloride  and  oxalate  to  the  filtrate  ;  a  fine  white 
precipitate,  insoluble  in  acetic  acid,  indicates  Cal- 
cium (traces). 21 

21.  Add  ammonic  chloride  and  carbonate  to  F.  19,  or 
to  the  liquid  already  containing  ammonic  carbon- 
ate in  sliglit  excess,  and  which  gave  no  flocculent 
precipitate  with  the  reagent,  boil  the  mixture,  fil- 


DETECTION    OF   THE    BASIC    ELEMENTS.  143 

ter,  add  ammonia  in  excess  to  the  clear  and  cooled 
filtrate,  filter  again  if  this  reagent  produces  any- 
precipitate,  add  hydric  disodic  phosphate  to  the 
filtrate,  agitate  the  mixture  vigorously,  and  set  it 
aside  for  several  hours  if  no  precipitate  appears  at 
first.  A  white  crystalline  precipitate  appears, 
that,  if  formed  slowly,  adheres  to  the  sides  of  the 
tube  ;  with  the  magnifying  glass,  and  usually  with 
the  unassisted  eye,  the  crystals  are  seen  to  be  slen- 
der prisms.  Magnesium. 
Finis, 


1 1 


o  2 


-  .="'  cl  >  ^'  S  ^"^ 


^  {--  _-  MH      r.-—  ^    O  C>  O 

C/2  rt 


^  s= 


O  d 


II 


^Il^o^'l-S^ 


?S) 


c5 


d 


lo 


•pis- 

o  o  'o  !^  d 


—I     U-J  r—  ^  I 


t?'^:^;' 


5  cs 


S  ^  ^  >;  ^  r,  *& 


^^      o'Ei) 


r.-^S^W- 


S3 


iij'^^  g-Q  a.c;  ^-3 


to   fi 

rf.2 
o  t 
H  o 


A.  la    o  '^■^  p^ 


t3' 


i^' 


O     ^H 


T3  :i  ^ 


<  o 


"m  ^    O    ^     '-^  — 

o  c  ■>  ^  *  o  S^ 


Cue  2ti 

p  -  '^    - 


t^  »        »r  -^  rt  O  P  ._  -^ 


<5  o 


_G=«    C    >   O 


i^'^ 


«    ri    ll    —    ^  '^Ki 


r   '^ 

c5  r 

10 

^  . 

0 

•Iq 

02  I 

..w 

r- 

^d 

^ 

a-^ 

rS    ^ 

w 

tf) 

I   S 

c 

p:^  O  P-i  |i|  t>H  Pi, 


§    89.       OCCURKENCE    OF   SUBSTANCES.  145 

C. 

For  the  mode  of  occurrence  of  the  substances  for  whose 
detection  directions  are  given  in  the  preceding  pages,  in 
agricultural  materials  and  products,  consult  Table  X,  ex- 
cept in  case  of  the  following,  which  are  not  widely  dis- 
tributed, or  whose  occurrence  presents  comparatively  less 
interest,  because  they  have  not  been  quantitatively  esti- 
mated in  these  materials  or  products. 

Acid,  acetic,  besides  occurring  in  vinegar,  which  re- 
sults from  the  action  of  the  air  on  alcoholic  liquors,  is 
found  among  the  products  of  the  putrefaction,  or  of  the 
destructive  distillation  of  organic  matter. 

Acid,  citric,  is  found  in  lemons,  and  in  most  other  acid 
fruits^  such  as  gooseberries,  cherries,  etc. 

Acid,  lactic,  is  the  acid  of  sour  milk,  and  is  found  also 
in  some  animal  juices,  and  sometimes  in  urine. 

Acid,  malic,  is  found  in  unripe  apples,  and  in  most  un- 
ripe fruits,  together  with  citric  acid,  and  also  in  potatoes, 
in  many  roots,  and  in  the  stems  and  leaves  of  many 
plants,  such  as  rhubarb,  tobacco,  etc. 

Acid,  tartaric,  is  found,  like  malic  acid,  in  many  fruits, 
and  particularly  in  the  grape  ;  it  occurs  also  in  the  roots, 
stems,  and  leaves,  of  many  plants. 

Arsenic  may  be  found  occasionally  in  superphosphates, 
where  it  was  derived  from  the  sulphuric  acid  used  in  the 
manufacture  of  the  article ;  it  is  also  a  frequent  and  dan- 
gerous ingredient  of  bright  green  pigments. 

Barium  may  sometimes  be  found  as  a  silicate  in  some 
common  rocks,  and  hence  in  soils. 

Copper  may  sometimes  be  found  in  culinary  products 
where  vessels  made  of  the  metal  or  its  alloys  have  been 
used ;  it  is  a  frequent  and  harmful  ingredient  of  bright 
green  pickles 

7 


146  §   89.      SPECIAL   METHODS   OF   ANALYSIS. 

Cyanogen  is  sometimes  to  be  found  among  the  products 
of  the  decomposition  of  nitrogenous  organic  matter  in 
the  presence  of  strong  bases,  particularly  if  the  decom- 
position has  been  aided  by  heat. 

Ferrocyanogcn  is  a  product  of  the  decomposition  of 
nitrogenous  animal  matters  by  heat,  in  the  j)resence  of  a 
strong  base  and  iron. 

Iodine  is  very  widely  but  sparingly  diifused. 

Lead  may  sometimes  be  found  in  water  that  has  been 
in  contact  with  it,  and  in  superphosphates ;  in  this  latter- 
case  it  is  derived  from  the  sulphuric  acid  used  in  the 
manufacture  of  the  fertilizer;  it  is  also  a  common  ingfre- 
dient  of  pigments. 

Manganese  occurs  in  nearly  all  soils,  and  is  generally 
found,  at  least  in  traces,  in  plants,  and  whatever  is  pro- 
duced from  them. 

Zinc  may  occur  in  soils  in  the  neighborhood  of  beds  of 
zinc  ore,  and  in  the  ashes  of  j)lants  grown  on  such  soils. 

II. 

SPECIAL     METHODS    OF     QUANTITATIVE     SEPARATION    OF 
SUBSTANCES. 

Under  this  head  a  few  special  methods  of  quantitative 
separation  of  substances,  that  often  occur  in  agricultural 
chemical  analysis,  are  described  with  full  details  and  di- 
rections, and  in  a  manner  convenient  for  reference.  In 
this  way  much  repetition  is  avoided  in  the  chapters  treat- 
ing of  special  analyses. 

By  consulting  Table  X,  at  the  close  of  the  book,  the 
analyst  may  ascertain  how  much  he  will  probably  find  of 
each  of  the  constituents  of  the  compound  he  is  about  to 
analyze,  and,  knowing  the  strength  of  his  reagents,  he 
can  form  some  idea  as  to  the  quantities  of  these  to  be  used 
to  pro'duce  complete  precipitation. 


§    90.       DESICCATION.  147 

DESICCATION. 

90.  One  of  the  more  frequent  determinations  in  agri- 
cultural analysis  is  that  of  water,  ash,  and  organic  matter. 

In  the  elimination  of  water,  or  the  desiccation  of  the 
substance  or  solution,  the  object  may  be  to  determine  the 
hygroscopic  water  of  the  substance,  or  it  may  be  the 
estimation  of  the  total  amount  of  solid  matter  in  a  solu- 
tion. 

a.  For  the  estimation  of  hygroscopic  moisture,  dry  the 
substance  well  in  the  air,  so  that  it  shall  be  thoroughly 
air-dried,  or  under  a  bell-jar  over  sulphuric  acid,  as  may 
be  directed  in  each  special  case ;  then  heat  a  weighed 
quantity  of  it  in  a  watch-glass  in  the  steam  or  air-bath  to 
the  temperature  indicated  in  each  case,  as  long  as  it  loses 
weight ;  while  weighing  the  substance,  it  should  be  en- 
closed between  two  watch-glasses  that  fit  well  together 
by  their  ground  edges. 

b.  Sometimes,  as  in  the  case  of  gypsum  containing  no 
volatile  matters  but  water,  the  substance  can  be  ignited 
at  once  ia  a  covered  crucible.  A  gentle  heat  should  be 
applied  at  first,  and  the  temperature  should  be  gradually 
raised,  at  least  almost  to  a  red  heat  in  some  cases. 

c.  When  the  substance  contains  a  large  amount  of  wa- 
ter, as  in  the  case  of  the  green  parts  of  plants,  it  is  best 
to  dry  a  large,  weighed  quantity  in  a  drying-chamber,  at 
from  60°  to  80°  C,  determine  the  loss  of  weight  at  this 
temperature,  and  then  proceed  as  in  a,  with  from  3  to  6 
grms.  of  this  partly  dried  substance. 

d.  Sometimes  the  substance  to  be  dried  contains  other 
volatile  ingredients,  as  ammonia  for  example ;  in  this 
case  the  desiccation  must  be  performed  in  a  current  of 
dry  air,  or  an  inactive  gas,  like  hydrogen,  by  means  of 
which  the  volatile  products  are  carried  into  some  absorb- 
ing solution.  Procure  a  deep  water-batn,  through  which 
a  tube  of  the  same  material  passes  laterally,  and  projects 


148  §    90.       SPECIx\L   METHODS    OF   ANALYSIS. 

a  little  beyond  the  sides  ;  weigh  the  substance  out  in  a  small 
porcelain  or  platinum  boat,  and  insert  the  boat  in  a  glass 
tube  open  at  both  ends,  and  drawn  out  and  bent  down  at 
one  end  ;  put  this  glass  tube  in  the  copper  tube  of  the  wa- 
ter-bath, immerse  the  end  of  the  glass  tube,  that  is  bent 
downwards,  in  a  measured  quantity  of  standard  sulphuric 
acid,  and  connect  the  other  end  with  an  apparatus  from 
Avhich  dry  hydrogen  is  evolved.  Apply  heat  to  the  water- 
bath,  and  when  the  desiccation  is  completed,  remove  the 
boat,  rinse  the  glass  tube  into  the  flask  containing  the 
acid,  boil  the  acid  a  little  to  expel  carbonic  acid,  that 
misrht  have  been  carried  over  with  the  ammonia,  and 
titrate  with  soda  solution  in  the  usual  manner  (§  45,  c). 

e.  For  the  estimation  of  the  amount  of  solid  substances 
in  a  solution^  evaporate  a  measured  or  weighed  quantity 
on  the  water-bath,  and  dry  the  residue  at  the  temperature 
indicated  in  each  particular  case ;  this  temperature  may 
range  all  the  way  from  100°  to  180°  C. 

f.  If  the  liquid  contains  other  volatile  matters  besides 
water,  as  in  the  case  of  urine,  which  may  give  off  am- 
monia when  heated,  put  it  in  a  porcelain  or  a  platinum 
boat,  which  has  been  previously  about  two-thirds  filled 
with  coarsely  pounded  and  well-washed  glass  or  coarse 
quartz  sand,  dried  at  100°,  and  weighed,  and  carry  on  the 
evaporation  as  in  the  case  of  a  solid  evolving  ammonia 
when  heated  (d). 

g.  If  the  solution  contains  substances  that  are  decom- 
posed at  a  temperature  above  100°,  and  yet  it  is  difficult 
to  dry  the  residue  left  on  evaporation  of  the  liquid  thor- 
oughly at  that  temperature,  imbed  the  dish  containing 
the  residue  in  sand  that  is  heated  to  100°  C,  put  the 
whole  over  a  dish  of  concentrated  sulphuric  acid  under 
the  receiver  of  the  air-pump,  and  exhaust  the  air ;  after 
the  sand  has  cooled,  repeat  the  process  with  a  fresh  quan- 
tity of  heated  sand,  and  so  on  as  long  as  there  is  any  loss 
of  weiorht. 


§    91.       INCINERATION.  149 

h.  If  the  substance  in  solution  is  liable  to  form  hard 
clumps  on  drying  that  retain  water  mechanically  enclosed, 
and  yet  the  residue  cannot  be  heated  much  above  100  C, 
mix  it  with  ^  |,  or  '  |g  of  its  weight  of  rather  finely  pulver- 
ized crystallized  gypsum,  or  of  pure  ignited  baric  sul- 
phate, that  has  been  artificially  prepared,  or  with  3  or  4 
times  its  weight  of  well-washed  fine  sand.  If  gypsum  is 
used,  it  should  be  tested  beforehand,  to  see  whether  it 
loses  any  weight  at  100°.  The  mixture  should  be  well 
stirred  as  the  evaporation  approaches  dryness.  Heat  the 
residue  at  100°  in  the  usual  manner  as  long  as  it  loses 
weight. 

INCINERATION,  OR  ESTIMATION  OF  ORGANIC  MATTER. 

91.  The  dried  residues  obtained  in  the  preceding  sec- 
tion are  often  examined  for  organic  matter  by  ignition 
until  this  matter  is  burned  away,  or  incineration. 

a.  The  ignition  is  performed  in  a  platinum  dish  or  cru- 
cible at  as  low  a  temperature  as  possible,  with  provision 
for  the  access  of  air  to  the  substance  along  the  surface  of 
the  lid  of  the  crucible,  as  directed  for  the  incineration  of 
filters  (§  40)  ;  or  a  piece  of  platinum  foil  may  be  bent  so 
as  to  rest  on  the  bottom  of  the  dish  and  on  the  rim,  and 
extend  some  distance  beyond  the  latter. 

h.  A  portion  of  the  original  solid  substance  may  be  in- 
cinerated at  once  in  the  muffle  furnace,  as  described  in 
§  123,  c,  under  preparation  of  the  ash  of  plants  for  analy- 
sis. Then,  on  subtracting  from  the  loss  of  weight  iu  this 
trial  the  amount  of  water  in  the  quantity  of  substance 
taken,  as  may  be  calculated  from  the  results  of  the  esti- 
mation of  hygroscopic  water  in  another  portion  of  the 
substance,  the  remainder  will  be  the  organic  matter,  or 
other  volatile  matter  besides  water. 

c.  A  part  of  the .  carbon  sometimes  obstinately  resists 


150  §    91.       SPECIAL    METHODS    OF    ANALYSIS. 

combustion ;  to  eliminate  this,  one  of  two  courses  may- 
be followed. 

1.  Exhaust  the  mixture  of  ash  and  coal  with  hot  water, 
collect  the  insoluble  part  on  the  filter,  wash,  dry,  and  ig- 
nite it ;  the  coal  will  generally  be  found  to  burn  much 
more  readily  after  this  treatment,  and  the  ash  can  more- 
over be  heated  to  a  higher  temperature  than  before  with- 
out fear  of  loss.  Add  the  ash  so  obtained  to  the  aqueous 
extract  and  washings,  evaporate  to  dryness,  ignite  gently, 
and  weigh. 

2.  Or,  weigh  the  mixture  of  ash  and  unconsumed  car- 
bon, determine  carbonic  acid  (d)  in  the  whole  or  a  j)or- 
tion  of  it,  collect  what  is  insoluble  in  the  nitric  acid  in  the 
determination  of  the  carbonic  acid,  on  a  dried  and  weigh- 
ed filter,  wash  it  well,  dry  at  110°  C,  weigh,  ignite  until 
the  carbon  is  completely  burned,  and  weigh  again.  The 
loss  of  weight  gives  the  unburned  carbon  in  that  portion 
of  the  original  ash  taken ;  calculate  the  amount  of  coal 
for  the  whole  quantity  of  the  original  mixture  of  ash, 
including  carbonic  acid  and  coal,  and  deduct  it  from  the 
same. 

d.  A  portion  of  the  carbon  in  the  organic  part  of  the 
substance  ignited  may  remain  behind  in  combination  with 
the  metallic  oxides  as  carbonic  acid ;  sinca  this  does  not 
properly  belong  to  the  ash  or  inorganic  part  of  the  sub- 
stance, it  should  be  determined  and  deducted  from  the 
total  weight  of  the  ash. 

For  this  purpose  estimate  the  carbonic  acid  (§  60)  in  a 
i:)ortion  of  the  ash,  or  the  whole  of  it,  according  to  the 
quantity  in  hand,  calculate  the  amount  for  the  whole 
quantity  of  the  ash,  if  only  a  portion  was  used  for  the 
analysis,  and  deduct  it  from  the  same. 

A  substance  may,  however,  contain  a  notable  quantity 
of  carbonic  acid  before  ignition,  as,  for  example,  a  soil 
with  carbonate  of  lime  in  it.  In  this  case  the  ignited 
residue  should    bo   moistened  with  ammonic  carbonate, 


§    91.       QUANTITATIVE   METHODS.  151 

carefully  dried,  gently  ignited,  and  weighed,  and  the 
operation  must  be  repeated  as  long  as  there  is  any  gain  in 
weight,  in  order  to  be  sure  that  there  is  at  least  as  much 
carbonic  acid  in  the  substance  after  ignition  as  before. 
Then  determine  carbonic  acid  in  the  ash,  or  a  portion  of 
it,  and  in  a  portion  of  the  original  substance ;  the  excess 
in  the  ash  over  what  was  in  the  quantity  of  substance 
taken  is  to  be  subtracted  from  the  weight  of  the  ash. 

e.  Small  quantities  of  organic  matter,  as  in  water,  may 
be  determined  by  the  following  volumetric  j^rocess  (Kuhel^ 
Fresenius^s  Zeitschrift^  6,  252). 

Dissolve  about  0.4  grm.  of  crystallized  potassic  per- 
manganate in  1  litre  of  water,  and  also  0.398  grm.  of  pure 
oxalic  acid  in  1  litre  of  water. 

Put  100  c.c.  of  distilled  water  and  10  c.c.  of  a  dilute 
sulphuric  acid,  containing  30  grms.  of  concentrated  acid 
in  100  c.c,  in  a  flask  of  about  300  c.c.  capacity,  heat  the 
mixture  to  boiling,  add  3-4  c.c.  of  the  permanganate  so- 
lution, boil  the  red  liquid  5  minutes,  remove  the  lamp,  and 
add  10  c.c.  of  the  solution  of  oxalic  acid  ;  potassic  per- 
manganate is  then  cautiously  added  from  a  burette  or  pi- 
pette, with  constant  stirring,  until  a  faint  red  color  ap- 
pears throughout  the  liquid.  The  total  amount  of 
permanganate  added,  corresponding  to  the  10  c.c.  of  the 
oxalic  acid  solution,  =  2  milligrammes. 

Now,  to  make  a  determination  of  organic  matter  in  a 
sample  of  drinking  water,  for  instance,  boil  100  c.c.  of  the 
water  in  a  flask  of  400  or  500  c.c.  capacity,  down  to  ''\^  its 
initial  volume,  to  decompose  ammoniacal  compounds  that 
are  very  liable  to  be  present  in  such  a  water,  by  means  of 
the  calcic  carbonate  that  is  also  nearly  always  present ; 
add  distilled  water  until  the  original  volume  is  nearly  re- 
stored, and  10  c.c.  of  the  dilute  sulphuric  acid ;  heat  to 
boiling,  add  5  or  6  c.c.  of  the  permanganate  solution,  and 
boil  5  minutes,  whereby  the  red  color  should  not  be  de- 
stroyed ;  then  add  10  c.c.  of  the  oxaHc  acid,  and  restore 


152  §    92.       SPECIAL   METHODS    OF    ANALYSIS. 

the  red  color  by  adding  the  permanganate  solution  from 
the  burette  as  before.  The  permanganate  added  this  time 
is  consumed  in  oxidizing,  not  only  the  10  c.c.  of  oxalic 
acid  that  was  added  to  the  solution,  but  also  other  organic 
matter,  and  therefore  more  permanganate  will  be  required 
than  when  the  oxalic  acid  was  mixed  with  distilled  water, 
as  in  the  first  experiment.  Multiply  the  number  of  milli- 
grammes of  permanganate  in  this  additional  quantity  of 
the  solution  used,  by  5,  for  the  organic  matter,  expressed 
in  milligrammes.  The  determination  is  only  an  approxi- 
mate one,  since  different  kinds  of  organic  matter  require 
difi'erent  amounts  of  oxygen  for  their  complete  oxidation, 
while  in  the  above  estimation  it  is  assumed  that  the  same 
amount  is  consumed  by  the  same  quantity  of  organic  mat- 
ter of  whatever  kind. 

92.  Estimation  of  Sulphur  {and  Chlorine)  in  Organic 
Compounds. 

Fuse  2  parts  of  a  mixture  of  pure  caustic  potassa 
free  from  sulphuric  acid  (or  chlorine)  with  '|g  part  of  pure 
potassic  nitrate  in  a  silver  dish,  with  the  addition  of  a 
little  water.  When  the  mixture  is  cold,  add  1  part  (3  to 
4  grms.)  of  the  finely  pulverized  substance,  fuse  the 
whole  with  constant  stirring  with  a  silver  spatula,  and 
continue  the  application  of  the  heat  until  the  mass  has 
become  quite  white ;  if  it  does  not  readily  become  so,  a 
little  more  potassic  nitrate  may  be  added. 

Dissolve  the  fused  substance  in  dilute  nitric  acid,  evap- 
orate to  dryness,  and  eliminate  silica  (§  58,  a,  1),  and  in 
the  filtrate  from  this,  precipitate  the  sulphuric  acid,  into 
which  the  sulphur  in  the  original  substance  has  been  con- 
verted by  oxidation,  with  baric  chloride  (§  59),  or  with 
baric  acetate,  if  chlorine  is  to  be  determined  in  the  filtrate 
from  the  baric  sulphate ;  the  chlorine  in  this  filtrate  is 
precipitated  by  argentic  nitrate  (§  63,  a). 

93.  Separation  and  determination  of  Potassium^  Sodi- 


§    93.       QUANTITATIVE    METHODS.  153 

wm,  Calcium^  Magnesium^  Alitminium,  Iron,  and  Man- 
ganese, and  Phosphoric  and  Sulphur ic  acids. 

This  is  one  of  the  most  frequently  recurring  separations 
in  agricultural  chemical  analysis. 

For  the  best  general  method  of  separation  in  each  par- 
ticular case,  the  analyst  will  be  referred  tg  one  of  the  ta- 
bles at  the  end  of  this  section,  in  which  the  whole  course 
to  be  followed  will  be  marked  out  in  a  few  words,  while 
more  detailed  descriptions  will  be  given  in  the  following 
paragraphs  of  some  of  the  necessary  manipulations  men- 
tioned in  the  table. 

A.  Precipitation  of  almnina,  X\fi^,  ferric  oxide,  Yefi^, 
Sindi phosphoric  acid  (anhydride),  PjO^.,  and  estimation  of 
the  two  bases. 

If  the  substance  contains  a  notable  proportion  of  or- 
ganic matter,  this  should  first  be  destroyed  in  the  solu- 
tion, and  the  iron  completely  oxidized  to  ferric  oxide  at 
the  same  time,  by  treatment  with  an  active  oxidizing 
agent. 

This  oxidation  may  be  effected  by  passing  chlorine  gas 
through  the  solution  until  it  is  nearly  saturated  ;  if  this 
course  is  followed,  the  solution  should  be  heated  after- 
wards, until  the  excess  of  chlorine  is  entirely  expelled. 

Or,  instead  of  using  chlorine,  the  solution  may  be  evai> 
orated  nearly  to  dryness,  and  sodic  or  potassic  hydrate 
added  in  slight  excess,  and  sodic  carbonate  and  a  little  so- 
dic or  potassic  nitrate ;  then  dry  the  mixture  completely 
in  a  platinum  dish,  and  ignite  the  residue  gently  until  the 
organic  matter  is  destroyed  ;  exhaust  the  mass  with  water, 
treat  it  with  dilute  hydrochloric  acid,  add  this  solu- 
tion and  the  washings  to  the  aqueous  one,  and  proceed  as 
directed  below  for  the  estimation  of  ferric  oxide,  etc.  If 
a  residue  remains  that  is  insoluble  in  hydrochloric  acid, 
dry,  ignite,  and  w^eigh  it,  and  add  the  amount  to  the 
silicic  acid  already  obtained. 
7"* 


154  §    93.       SPECIAL   METHODS    OF    ANALYSIS.       • 

1.  Case  in  which  there  is  enough  ahimi?ia  and  ferric 
oxide  present  to  combine  with  all  the  phosphoric  acid. 
The  filtrate  from  the  precipitate  by  sodic  acetate,  obtained 
in  a  qualitative  test  in  the  manner  described  below,  gives 
no  reaction  for  phosphoric  acid  with  aramonic  molybdate. 

To  the  not  too  concentrated  solution  add  sodic  carbon- 
ate with  constant  stirring,  until  a  few  scattered  flakes  of  a 
precipitate  remain  permanent,  heat  to  boiling,  remove  the 
lamp,  and  add  immediately  an  excess  of  a  boiling  hot  so- 
lution of  sodic  or  ammonic  acetate  ;  this  reagent  precipi- 
tates all  the  AI2O3,  Fe203,  and  P^O^ ;  filter  rapidly  while 
hot,  and  wash  the  contents  of  the  filter  with  boiling  water, 
containing  a  little  ammonic  acetate  ;  dissolve  the  precipi- 
tate, without  drying  it,  in  hot,  dilute  hydrochloric  acid, 
wash  the  filter  out  well,  mix  the  solution  and  washings  by 
vigorous  stirring,  add  water,  if  it  is  necessary,  to  bring 
the  liquid  to  such  a  volume  that  it  can  be  conveniently 
divided  in  two  equal  parts,  and  mix  carefully  again  by 
stirring,  divide  it  accurately,  precipitate  one  part  with 
ammonia  in  slight  excess,  as  directed  for  the  precipitation 
of  alumina  (§  51),  filter,  wash  with  hot  water,  dry,  ignite 
precipitate  and  filter  separately,  and  weigh  ;  the  result, 
multiplied  by  two,  gives  the  total  amount  of  Al^Og,  Fe203, 
and  P2O5  in  the  undivided  solution. 

Keduce  the  ferric  to  ferrous  oxide  in  the  other  half  of 
the  solution,  and  estimate  the  iron  with  potassic  perman- 
ganate (§  52,  h)  •  or,  as  a  sulphuric-acid  solution  is  better 
adapted  for  that  process,  this  half  of  the  solution  may  be 
precipitated  with  ammonia  also,  and  the  precipitate  wash- 
ed, and  dissolved,  without  drying  it,  in  dilute  sulphuric 
acid.  The  amount  of  ferric  oxide  being  estimated  from 
the  result,  multiply  by  two  and  thus  get  the  quantity  of 
Fe^Og  in  the  undivided  solution. 

The  difference  between  the  total  weight  of  Al^Og, 
Fe^Og,  and  P^O,^,  and  the  sum  of  the  Fe^Og,  as  determined 
above,  and  the  P^O^  to  be  determined  in  another  portion 


§    93.       QUAXTITATIVE    METHODS.  155 

of  the  solution  and  estimated  for  the  amount  of  solution 
taken  for  this  analysis,  will  give  the  Al^Og. 

2.  In  case  there  is  not  Fe^Og  and  Al^Og  enough  present 
to  combine  with  all  the  phosphoric  acid,  more  iron  must 
be  added,  until  a  drop  of  the  liquid,  on  a  watch-glass, 
gives  a  reddish  precipitate  with  a  little  ammonia,  and  the 
amount  of  iron  so  added  is  to  be  subtracted  from  the  total 
amount  found  subsequently.  This  addition  of  iron  is 
most  conveniently  made  in  tlie  form  of  a  carefully  meas- 
ured quantity  of  an  accurately  titrated  solution  of  ferric 
chloride  (Fe^ClJ,  about  '1^  the  strength  of  the  reagent  or- 
dinarily used.     Proceed  then  as  in  1. 

B.  The  method  of  removing  phosphoric  acid  by  means 
of  metallic  tin  admits  of  the  determination,  in  a  conven- 
ient manner,  of  this  acid,  and  alumina,  ferric  oxide,  man- 
ganous  oxide,  lime,  and  magnesia,  in  the  same  portion  of 
the  solution. 

On  evaporating  to  dryness  to  remove  silica,  after  moist- 
ening the  dried  residue  with  concentrated  hydrochloric 
acid  in  the  usual  manner,  add  nitric  acid,  dilute  with 
water,  filter,  wash  the  insoluble  silica  on  the  filter,  evap- 
orate the  filtrate  and  washings  nearly  to  dryness,  or  until 
all  the  hydrochloric  acid  is  expelled,  dissolve  the  residue 
in  concentrated  nitric  acid,  heat  the  solution  to  boiling  in 
a  beaker  covered  with  a  large  watch-glass  or  an  inverted 
funnel,  and  add  pure  tin  in  small  grains,  and  in  small 
portions  at  a  time,  to  an  amount  about  six  times  as  great 
as  that  of  the  phosphoric  acid  supposed  to  be  present,  di- 
gest the  mixture  5  or  C  hours  in  a  warm  place,  dilute  and 
decant  the  clear  supernatant  liquid  on  the  filter,  and  wash 
the  precipitate,  containing  stannic  oxide,  stannic  phos- 
phate, and  perhaps  some  alumina  and  ferric  oxide,  several 
times  by  decantation  with  boiling  dilute  nitric  acid,  and 
finally  with  a  little  water ;  then  digest  it  with  amnion io 
sulphide,  wash  the  undissolved  aluminic  hydrate  and  fer- 
rous sulphide  first  with  hot  ammonic  sulphide,  and  then 


156  §    93.       SPECIAL    METHODS    OF    ANALYSIS. 

with  water  to  the  successive  portions  of  which  less  and 
less  amnionic  sulphide  is  added  ;  dissolve  it  in  dilute  hy- 
drochloric acid,  and  add  the  solution  to  the  first  filtrate 
from  the  stannic  oxide,  etc.,  containing  the  main  part  of 
the  alumina  and  ferric  oxide. 

The  solution  obtained  by  treating  the  precipitated 
stannic  oxide  and  phosphate,  etc.,  by  ammonic  sulphide, 
contains  all  the  j^hosphoric  acid  {Baehei\  Zeitschnft  filr 
die  gesammten  Naturwissenschaften^  1864, 293.  Fresenius's 
Zeitschrift^  4,  122)  /  if  its  volume  has  been  increased  to  a 
considerable  bulk  by  the  washings  of  the  precipitate  of 
aluminic  hydrate  and  ferrous  sulphide,  concentrate  it  by 
evaporation,  filter  again  if  not  clear,  and  precipitate  the 
phosphoric  acid  with  magnesia  mixture  in  the  usual  man- 
ner (§  61,  a). 

In  the  filtrate  from  the  precipitated  stannic  oxide  and 
j)hosphate,  etc.,  determine  the  bases,  as  directed  in  A,  C, 
and  D,  except  that,  since  the  precipitate  by  sodic  acetate 
in  A  contains  no  phosphoric  acid,  the  difference  between 
the  total  weight  of  the  precipitate  by  ammonia,  and  the 
weight  of  the  ferric  oxide,  as  determined  by  potassic  per- 
manganate, gives  the  alumina. 

The  method  is  not  applicable  in  the  presence  of  hydro- 
chloric acid  or  chlorides. 

C.  Precipitation  of  manganic  hinoxide^  MnO„,  in  the 
filtrate  from,  the  precipitate  by  sodic  acetate  in  A. 

Heat  this  filtrate,  which  should  he  free  from  ammonic 
salts,  and  tolerably  concentrated,  to  50  or  60°  C,  and  con- 
duct chlorine  gas  through  it  until  it  is  saturated,  or  as  long 
as  any  precipitate  is  formed ;  filter  out  the  precipitate,  add 
more  sodic  acetate  to  the  filtrate,  pass  chlorine  through 
again,  and  add  this  second  precipitate  to  the  first,  if  any 
is  obtained.  Wash  the  precipitated  manganic  hydrate 
first  by  decantation  and  then  on  the  filter,  dry  this,  sepa- 
rate the  precipitate  from  it  as  completely  as  possible,  burn 
it  and  dissolve  the  ash  and  the  precipitate  in  concentrated 


§    93.       QUANTITATIVE    METHODS.  157 

hydrochloric  acid,  remove  any  great  excess  of  acid  by 
evaporation,  and  precipitate  the  solution  with  sodic  car- 
bonate.    (§  53.) 

Heat  the  filtrate  from  the  precipitate  by  chlorine  as  long 
as  any  odor  of  the  gas  is  perceived. 

D.  Precipitation  of  llme^  CaO^  and  magnesia,  MgO^ 
in  the  filtrate  from  the  precipitate  by  sodic  acetate  (A)  or 
by  chlorine  (C).  Neutralize  the  solution  with  ammonia  if 
it  is  acid,  and  proceed  as  directed  in  §  50  6  to  precipitate 
lime  with  ammonic  oxalate,  and  magnesia  with  hydric 
disodic  phosphate. 

M  Separation  and  determination  of  sulphuric  acid 
{anhydride),  SO^.  Precipitate  the  acid  with  baric  chlo- 
ride in  the  slightest  possible  excess,  and  preserve  the 
washings  with  water  alone,  while  those  with  cupric  acetate 
may  be  thrown  away.     (§  59.) 

i^  Estimation  of  phosphoric  acid  (anhydride),  P^O^, 
in  the  filtrate  from  the  precipitate  by  baric  chloride. 

Add  ammonia  in  slight  excess  only,  if  much  iron  or 
aluminum  is  present,  otherwise  a  mixture  of  ammonia  and 
ammonic  carbonate,  as  long  as  a  precipitate  is  formed, 
digest  the  mixture  a  considerable  time  until  the  free  am- 
monia is  expelled,  wash  the  precipitate  well,  dissolve  it, 
without  drying  it,  in  nitric  acid,  and  eliminate  PjO^  with 
ammonic  molybdate.     (§  61.  b.) 

G.  Elimination  of  the  cdkaline  metals  as  chlorides. 

(1.)  Precipitate  SO3  by  the  slightest  possible  excess  of 
baric  chloride,  if  this  has  not  already  been  done ;  evapo- 
rate the  mixture  on  the  water-bath  until  most  of  the  free 
acid  has  been  removed,  add  pure  milh  of  lime  in  slight 
excess,  digest  some  time  on  the  water-bath,  and  filter  out 
the  precipitated  Fe.Og  Aip^  MgO,  and,  SO3  and  P,0,. 
"Wash  the  precipitate  as  long  as  the  washings  make  argentic 
nitrate  turbid,  precipitate  the  excess  of  lime  in  the  concen- 
trated filtrate  and  washings,  by  ammonic  carbonate  con- 


158  §    93.       SPECIAL    METHODS    OF    ANALYSIS. 

taining  excess  of  ammonia,  let  the  precipitate  settle,  filter, 
evaporate  to  dryness,  and  ignite ;  dissolve  the  residue  in 
water,  and  precipitate  again  with  ammonia  and  ammonic 
carbonate,  filter,  evaporate  to  dryness,  and  ignite;  and  re- 
peat tliis  operation  as  long  as  these  reagents  cause  any 
turbidity;  finally,  ignite  gently,  weigh  the  alkaline  chlo- 
rides thus  obtained,  and  determine  potassium  and  sodium 
in  the  mixture  by  the  indirect  process  (§  46  d)^  or,  if  greater 
accuracy  is  desired,  precipitate  potassium  with  platinic 
chloride  (§  46  h), 

(2.)  Precipitate  the  SOg  in  the  boiling  solution  with 
baric  chloride  in  slightest  possible  excess,  if  this  has  not 
already  been  done,  evaporate  the  mixture  on  the  water- 
bath  until  most  of  the  free  acid  is  removed,  add  some  wa- 
ter and  then  ammonia  and  ammonic  carbonate  as  long  as 
a  precipitate  is  formed,  and  finally  a  little  ammonic  oxa- 
late, digest  on  the  water-bath,  filter,  and  wash  the  contents 
of  the  filter  carefully.  Evaporate  the  filtrate  and  wash- 
ings to  dryness  (§  37),  ignite  the  residue  to  expel  ammo- 
niacal  salts,  weigh  roughly,  and  add  a  quantity  of  a  con- 
centrated solution  of  pure  oxalic  acidxhixt  contains  enough 
of  the  acid  to  make  quadroxalate  with  an  amount  of  po- 
tassa  equivalent  to  all  the  bases  present,  evaporate  to  dry- 
ness, and  ignite  again.  By  this  process,  magnesia  and 
traces  of  lime,  baryta,  ferric  oxide,  etc.,  that  may  possibly 
be  present,  are  rendered  insoluble  in  water.  Treat  the  ig- 
nited residue  with  a  small  quantity  of  boiling  water,  throw 
it  on  a  filter,  wash  it  with  several  small  portions  of  boiling 
water,  as  long  as  anything  is  dissolved,  add  hydrochloric 
acid  in  slight  excess  to  the  filtrate  and  washings,  evaporate 
to  dryness,  and  ignite  the  residue  of  alkaline  chlorides 
gently,  weigh,  and  determine  potassium  and  sodium  by 
the  indirect  process  (§  46  d),  or  with  platinic  chloride 
(§  46  h). 

If,  when  these  chlorides  are  dissolved  in  water,  a  clear 
solution  is  not  obtained,  or  if  the  solution  has  a  basic  re- 


§    93,       QUANTITATIVE    METHODS.  159 

action,  it  should  be  evaporated  to  dryness  and  the  residue 
treated  with  oxalic  acid  again. 

(3.)  According  to  Stohmann  {Fresenius's  Zeitschrift,  5, 
306),  potassium  may  be  separated  out  at  once  by  platinic 
chloride  from  a  solution  containing  only  alkalies  and  alka- 
line earths. 

Having  precipitated  the  sulphuric  acid  completely  as 
above  in  the  boiling  solution  of  about  10  grms.  of  the 
substance,  filter  out  the  precipitate  if  the  quantity  of  it  is 
large  ;  if  but  small,  let  it  remain  in  the  liquid ;  dilute  the 
liquid,  when  cool,  to  1000  c.c.  and  mix  the  whole  thor- 
oughly together.  To  100  c.c.  of  the  clear  solution  add  an 
amount  of  platinic  chloride  containing  about  2  grms.  of 
the  metal,  evaporate  the  mixture  nearly  to  dryness,  and 
proceed  as  directed  for  the  separation  of  potassium  and 
sodium  by  platinic  chloride  (§  46  h).  The  method  is  based 
upon  the  fact  that  the  double  chlorides  of  calcium,  barium, 
and  magnesium,  and  platinum,  are  soluble  in  water  and 
alcohol,  as  well  as  the  double  chloride  of  sodium  and 
platin  um. 

H.  Reparation  oi  phosphor'iG  acid  alone. 

(1.)  Evaporate  the  hydrochloric  acid  solution,  contain- 
ing no  great  excess  of  iron  over  the  phosphoric  acid,  to 
dryness  on  the  water-bath,  to  eliminate  silica,  moisten  the 
perfectly  dried  residue  with  about  2  c.c.  of  concentrated 
hydrochloric  acid,  and,  after  a  while,  add  about  10  c.c.  of 
concentrated  nitric  acid  (Sp.  Gr.  =  1.2)  for  every  0.15 
grm.  of  phosphoric  acid  supposed  to  be  present,  dilute 
with  water,  filter  if  necessary,  and  wash  the  residue  of  in- 
soluble silica ;  evaporate  the  filtrate  and  washings  nearly 
to  dryness,  dissolve  the  residue  in  about  half  as  much 
concentrated  nitric  acid  as  was  added  before,  and  proceed 
to  precipitate  phosphoric  acid  with  amnionic  molybdate 
(§  61  h).     [Fresenius's  Zeitschrift,  4,  404.) 

(2.)  To  the  solution  of  the  phosphate  add  ferric  chloride 
in  slight  excess  over  the  phosphoric  acid,  if  there  is  not 


160  §    93.       SPECIAL    METHODS    OF    ANALYSIS. 

already  enough  alumina  and  ferric  oxide  present,  so  that, 
when  the  solution  is  nearly  neutralized  with  sodic  hydrate, 
heated  to  boiling  aud  precipitated  with  sodic  acetate  in 
excess,  the  filtrate  gives  no  reaction  for  phosphoric  acid. 

Nearly  neutralize  the  solution  with  sodic  hydrate  or 
carbonate,  heat  to  boiling,  and  add  sodic  acetate  in  excess, 
filter  the  mixture  while  hot,  wash  with  boiling  water  con- 
taining a  little  ammonic  acetate,  dissolve,  without  igniting, 
in  dilute  hydrochloric  acid,  wash  the  filter  out  carefully, 
dilute  the  solution  moderately,  add  rather  a  large-quantity 
of  citric  acid,  and  then  an  excess  of  ammonia ;  if  enough 
citric  acid  is  present,  the  solution  remains  clear.  Finally, 
add  magnesia  mixture  to  the  solution,  and  precipitate 
phosphoric  acid  in  the  usual  manner.     (§  61  a.) 

The  solution  should  not  contain  too  large  an  excess  cf 
hydrochloric  acid,  and  a  great  excess  of  citric  acid  must  bo 
avoided  also.  The  method  gives  the  best  results  when  the 
proportion  of  phosphoric  acid  is  large,  as  compared  with 
the  alumina  and  ferric  oxide ;  if  these  oxides  are  present 
in  large  quantity,  it  may  be  necessary  to  re-dissolve  the 
precipitate  by  magnesia  mixture  in  hydrochloric  acid,  add 
citric  acid,  and  re-precipitate  the  phosphoric  acid  by  am- 
monia and  a  little  magnesia  mixture. 

(3.)  In  solutions  containing  a  great  excess  of  ferric  oxide, 
it  is  better  to  reduce  a  portion  of  this,  at  least,  to  ferrous 
oxide  before  precipitation  with  sodic  acetate. 

Heat  the  acid  solution  to  boiling,  remove  the  lamp,  add 
a  solution  of  sodic  sulphite  until  the  liquid  is  quite  color- 
less, and  sodic  carbonate  produces  a  white  precipitate ; 
then  boil  the  mixture  as  long  as  any  odor  of  sulphurous 
acid  is  evolved,  nearly  saturate  the  acid  with  sodic  carbon- 
ate, add  a  few  drops  of  chlorine  water,  then  sodic  acetate 
in  excess,  and  finally  more  chlorine  water  drop  by  drop, 
until  the  liquid  is  reddish,  and  boil ;  the  precipitate  con- 
tains all  the  alumina  and  phosphoric  acid,  mixed  with  but 
little  ferric  oxide ;  filter  it  out  quickly,  wash  it  with  a  lit- 


§  94.     QUANTITATIVE  :metiiods.  161 

tie  hot  water,  and  dissolve  it,  without  ignition,  either  in 
nitric  acid  and  eliminate  phosphoric  acid  with  the  aid  of 
amnionic  molybdate  (§  61,  b),  or  in  hydrochloric  acid  and 
precipitate  the  phosphoric  acid  with  magnesia  mixture  in 
the  presence  of  citric  acid,  as  above. 

(4.)  If  there  is  a  large  proportion  of  phosphoric  acid  in 
the  substance,  and  comparatively  little  ferric  oxide  and 
alumina,  the  nitric  acid  solution,  obtained  as  in  1,  may  be 
treated  with  metallic  tin,  as  described  in  J^. 

91.  Schemes  for  the  quantitative  separation  of  K.^  iVa., 
Ca.,  My,,  Fe.,  AL,  Mn.,  P,  0„  and  SO^, 

The  purpose  of  these  schemes  is,  to  present  a  birds- 
eye  view  of  the  various  courses  to  be  followed  for  the 
separation  of  the  bases  and  acids  given  in  this  list. 

For  the  details  of  the  manipulation  the  analyst  should 
always  follow  up  the  references  given  in  the  schemes  and 
in  §  93,  unless  he  is  perfectly  familiar  with  these  details, 
and  knows  them,  as  it  were,  by  heart. 

The  capital  letters  in  the  schemes  refer  to  paragraphs 
in  §  93,  the  small  letters  to  other  parts  of  the  schemes 
themselves. 


162 


§    94.       SPECIAL   METHODS    OF   ANALYSIS. 


PnOSPHORIC  ACID     IS   Oli    IS    NOT    IN    EXCESS   OVER   THE   ALUMINA  AND 
PERRIC   OXIDE. 

Divide  the  filtrate  from  the  silica  in  three  parts,  a,  b,  and  c. 


1.  Precipitate  SO3 
withBaCl,  filter.  (E.) 

2.  Precipitate  P2O5 
together  with  Fe,Ca, 
etc.,  with  NH4HO,or 
NH4HO  and  (NH4)2- 
CO3,  filter.     (F.) 

0.  Eliminate  K.  and 
Na.  as  chlorides, 


by  treat- 
ment with 

milk  of 
lime,  NH4- 
HO  and 
(NH4)2- 
CO3,  filtra- 
tion, evap- 
oration to 
dryness, 
ignition. 
G,  1. 


/3- 
by   evapo- 
ration to 
dryness, 
ignition, 
addition 
of  oxalic 
acid,  igni- 
tion, solu- 
tion in 
water,   fil- 
tration, 

and 

ignition. 

G,  2. 


1.  First  add  FcsCle  in 
slight  excess  over  the  P2- 
O5  if  AI2O3  and  FcaOg  are 
not  already  present  in 
excess  (see  A,  1);  then 
eliminate  the  acid, 


a. 
by   addition 

of  NH4HO 

in  slight  ex- 
cess,   diges- 
tion, filtra- 
tion, solu- 
tion of  pre- 
cipitate in 
HNO3  and 
precipita- 
tion of  P2O5 
with(NH4)2- 
M0O3. 

ILL 


by  addition 
of  NaHO 
until  nearly 
neutral,  pre- 
cipitation 
with  NaC2- 
H302(oruse 

of  NH4HO 

and  NH4C2- 
H3O2  if  alka- 
lies are  to 
be  determ- 
ined in  fil- 
trate); dis- 
solve pre- 
cipitate in 
HCl,  precip- 
itate P2O5 
with  mag- 
nesia mix- 
ture and 
citric  acid. 
H,  2. 


2.  Treat  filtrate  from 
precipitate  by  NH4HO  in 
a  or  NH4C2H3O2  in  /3  as 
under  a,  if  it  is  desired 
to  repeat  the  determina- 
tion of  alkalies. 


1.  First  add  an  accu- 
jratcly  titrated  solution 
I  of  FcaCls  in  proper 
'quantity  (see  A,  2)  if 
AI2O3  and  Fe203  are  not 
already  present  in  ex- 
cess over  the  P2O5;  then 
add  NasCOg  until  nearly 
neutral,  and  precipitate 
Fe,Al,P205  with  NaCs- 
H3O2 ;  dissolve  precipi- 
tate in  HCl,  divide  in 
halves,  precipitate  one- 
half  with  NH4HO,  filter, 
ignite,and  wei<^h  Al,Fe, 
P2O5.  Determine  Fein 
other  half  with  K2Mn2- 
Og,  at  once,  or  after  pre- 
cipitation w'ith  NH4HO 
and  solution  in  II2SO4. 
(A.) 

2.  First  Filtr.  — 
{From  the2yr€€.  by  KaCr 
B^O-i).  Concentrate  and 
precipitate  Mn  by  CI. 
(C.) 

3.  Second  Filtr. — 
{From  the  prec.  bij  CI.) 
Concentrate,precipitate 
Ca  with(NH4)2C204  (D). 

4.  Third  Filtr.— 
(From  the  prec.  by 
{NBi)^C^Oi.)  Concen- 
trate and  precipitate 
Mg.  with  Naali,  PO4 
(D). 


IL 

A  LARGE   EXCESS  OF    BOTU  ALUMINA  AND     FERRIC    OXIDE    IS    PRESENT. 

Divide  the  filtrate  from  the  silica  in  three  parts,  a,  b,  and  c. 


1.  Precipitate  SO3  with  Ba- 
Cl  and  filter.     (E.) 

2.  Eliminate  K  and  Na  as 
chlorides.  See  Scheme  I, 
a,  3. 


b. 

Treat  this 
portion  as 
directed  in 
Sclieme  I 
under  c. 


c. 

Reduce  the  ferric  to  fer- 
rous oxide  witli  sodic  sul- 
phite (H,3),  precipitate  all 
Al  and  P0O5  together  with 
little  Fe,  and  eliminate  P2O5 
as  under  a  or  j3,  Scheme  I,  b. 


§    94.       QUANTITATIVE    METHODS. 


163 


III. 

NO  ALUMINA  IS    PRESENT,   AND    PHOSPnORIC  ACID    IS    IN    EXCESS  OVER 

THE    IRON. 

Divide  tlic  filtrate  from  tlie  silica  in  two  parts,  a  and  b. 


Determine 

S03,F205,K 

and  Na,  as 

under  a, 

Scheme  I. 


b. 
1.  Add  an  aceui'ately  titrated  solution  of  FeaClg,  nearly' 
neutralize  the  solution  with  NasCOa,  precipitate  Fe  and 
P2O5  with  NaCsHgOQ  (A);  dissolve  the  precHpitute  in  HCl, 
divide  solution  in  two  equal  portions,  a  and  (i. 


Determine  Fe  with  per- 
manganate (A.) 


2^. 
Determine  P2O5  with  (NH4)2- 
M0O3  (H,  1)  or  citric  acid  and 
magnesia  mixture  (H,  2). 


3.  Determine  Mn,  Ca,  and  Mg,  in  the  filtrate  from  the 
precipitate  by  NaC2H302,  as  in  2,  3,  and  4,  under  c, 
Scheme  I. 


IV. 

NO  ALUMINA  OR  MANGANESE  IS  PRESENT,   AND   PUOSPHORIC  ACID  IS  IN 
EXCESS   OVER   THE    IRON. 

Proceed  as  in  III,  except  that  the  elimination  of  manganese  by  chlorine 
may  be  omitted. 


TO  DETERMINE  ALL  WITHOUT  DIVIDING  THE  SOLUTION. 

1.  To  the  filtrate  from  the  silica  add  the  titrated  solution  of  ferric 
chloride,  if  necessar.v,  (see  §  93,  A,  2),  nearly  neutralize  the  solution  with 
(NH4)2C03,  precipitate  Fe,  Al,  and  P2O5,  with  NH4C2H3O2,  dissolve  the 
precipitate  in  HCl,  and  divide  the  solution  in  two  equal  portions ;  pre- 
cipitate one  portion  with  NH4HO,  and  get  total  Al,  Fe,  and  PsOs;  heat 
the  ignited  residue  in  a  mixture  of  8  parts  of  concentrated  sulphuric 
acid  and  3  parts  of  Avater,  add  water,  and  determine  Fe  in  this  solution 
with  potassic  permanganate  (A) ;  eliminate  P2O5  in  the  other  portion  of 
the  solution,  with  the  aid  of  ammonic  molybdate,  or  magnesia  mixture 
in  the  presence  of  citric  acid.     (H.) 

2.  First  Filtrate.  {From  the  precip.  by  NRiCJIsO^.)  Evaporate 
to  dryness  and  ignite  the  residue  until  ammonic  salts  are  completely  ex- 
pelled; dissolve  in  water  acidified  with  HCl,  nearly  neutralize  the  solu- 
tion with  NaaCOa,  add  NaCaHgOj,  and  precipitate  Mu  by  CI.    (C.) 

3.  Second  Filtrate.  {From  the  precipitate  by  CI.)  After  removing 
excess  of  CI  by  heat,  precipitate  Ca  with  (NH4)2C204.    (D.) 

4.  Third  Filtrate.  {From  the  precip.  by  {NEi^C^Oi).  Precipitate 
SOgwithBaCl.    (E.) 


164  §    94.       SPECIAL   METHODS    OP    ANALYSIS. 

5.  Fourth  Filtrate.  {From  the  preclp.  1)]]  BaCl.')  Kemove  excess 
of  Ba  with  (NH4)2  COg,  evaporate  filtrate  to  dryuess,  ignite,  treat  with 
1120204,  (see  G,  2),  ignite,  exliaust  with  water,  and  treat  this  solution  for 
the  estimation  of  the  alkalies,  as  directed  for  the  treatment  of  the  cor- 
responding solution  in  G,  3. 

6.  Dissolve  the  residue  that  has  been  exJiausted  dy  water  as  above,  in  di- 
lute HCl,  filter  if  necessary,  and  precipitate  Mg  in  the  filtrate  with  NagH 
PO4  (§  50,  a). 

VI. 

TO  DETERMINE  ALL  EXCEPT   MANGANESE,   W^ITHOUT   DIVIDING  THE 
SOLUTION. 

Proceed  as  under  V,  except  that  the  evaporation  to  dryness,  ignition,  and 
treatment  with  01  for  the  estimation  of  Mn,  arc  to  be  omitted. 

VII. 

TO  DETERMINE  ALL  EXCEPT  MANGANESE  AND  PHOSPHORIC  ACID,  WITH- 
OUT  DIVIDING   THE   SOLUTION. 

Proceed  as  under  VI,  except  that  no  FcsCle  need  be  added,  and  that  one 

portion  of  the  solution  of  the  precipitate  by  NH4C2H3O0  is  to  be  used  for 

the  estimation  of  the  sum  of  the  Fe  and  Al  only,  and  the  other  portion 

for  the  determination  of  Fe.    (A.) 

VIII. 

TO     DETERMINE    ALL     EXCEPT    ALUMINIUM    AND    MANGANESE  WITHOUT 
DIVIDING  THE   SOLUTION. 

Proceed  as  under  VI,  except  that  one  portion  of  the  solution  of  the  pre- 
cipitate by  NH4C2H3O2  is  to  be  used  for  the  estimation  of  Fe,  and  the 
other  for  that  of  P2O3.     (A,  H.) 

IX. 

DETERMINATION    Or  ALL,   AND    ELIMINATION    OF    PHOSPHORIC  ACID    BY 
THE   TIN  PROCESS. 

Divide  the  filtrate  from  the  silica  in  tw^o  parts,  a  and  b. 


a. 

1.  Precipitate 
SO3  with  BaCl, 
and  filter.  (E.) 

2.  Eliminate  K 
and  Na  as  chlo- 
rides.     (See 

Scheme  I,  a,  3.) 


b. 

1.  Treat  the  concentrated  nitric-acid  solution  with 
Sn,  this  precipitate  by  NII4HS,  and  the  solution  so  ob- 
tained with  magnesia  mixture  (B). 

2.  First  Filtr.  (From  the  precip.  by  Sn.)  Precipi- 
tate Fe  and  Al  by  NallO  and  NaCoHgOo,  dissolve  the 
precipitate  in  HOI,  divide  solution  in  two  equal  purts, 
precipitate  one  part  by  NH4HO  to  get  total  Al  and  Fe, 
and  determine  Fe  in  the  otlier  part  (A). 

3.  Second  Filtr.  (From  the  lu-ecip.  by  NaOoHgOa.) 
Treat  tiiis  for  the  estimation  of  Mn,  Ca,  and  Mg,  as  in 
Selieme  I,  under  c,  3,  8  and  4. 


§  95.     SOILS.  165 

X. 

TO      DETERMINE     ALL     EXCEPT     MANGANESE,     WITHOUT     DIVIDING     THE 
SOLUTION. 

a.  Eliminate  P0O5  from  tlic  filtrate  from  the  silica,  bv  means  of  Sn 
(VIII,  b). 

b.  First  Filtr.  (From  tlie  precip.  by  Sn.)  Precipitate  Al  and  Fe  with 
NH4HO  and  NH4C2H3O2,  and  treat  this  precipitate  as  directed  for  the 
treatment  of  the  correspondin*^  one  by  NaCaHgOa  in  VIII,  b. 

c.  Second  Filtr.  Treat  this,  for  the  estimation  of  Ca,  SO3,  K,  Na,  and 
Mg,  as  directed  in  Scheme  V,  3,  4,  5  and  6. 


CHAPTER    Y. 

ANALYSIS    OF    SOILS    AND    ROCKS. 
I. 

SOILS. 

95i  The  following  general  method  of  analyzing  soils, 
by  Emil  WoliF,  was  approved  at  the  annual  meeting  of 
German  Agricultural  Chemists  in  Gottingen,  in"  1864, 
and  is  given  in  full  in  his  work  on  agricultural  analysis, 
referred  to  in  the  preface. 

In  his  introductory  remarks,  Prof.  Wolff  writes  :  "  Of 
course  it  is  not  essential  that  the  experienced  chemist 
should  follow  strictly  all  the  methods  for  the  separation 
and  quantitative  estimation  of  particular  components  of 
the  soil,  that  are  given  here  as  guides  for  the  beginner 
in  chemical  analysis,  and  are  used  by  me  ;  those  methods 
may  be  modified  in  many  cases  without  impairing  the 
accuracy  of  the  analytical  work.  But  it  is  necessary 
that  all  chemists  who  undertake  accurate  analyses  of 
soils  should  agree  to  follow  the  same  course  in  regard  to 


166  §    96.       ANALYSIS    OF    SOILS    AND    HOCKS. 

certain  important  points,  in  order  that  the  results  ob- 
tained by  different  workers  may  be  comparable  with 
each  other,  or  possess  any  lasting  practical,  or  scientific 
value. 

"  Such  essential  points,  concerning  which  agricultural 
chemists  should  aim  to  agree,  are,  the  manner  in  which 
the  sample  of  the  soil  is  to  be  taken  from  the  field,  the 
preparation  of  the  same,  and  the  quantity  to  be  taken 
for  analysis,  the  manner  of  performing  the  mechanical 
silt  (Schlamm)  analysis,  the  methods  of  determining  the 
coefficients  of  absorption  of  the  more  important  elements 
of  plant-food,  and,  above  all,  the  preparation  of  the  solu- 
tions or  extracts  of  the  soil  that  are  to  be  subjected  to 
chemical  analysis." 

He  says  also  in  another  place : 

"  Although  I  recognize  the  need  of  a  large  number  of 
full  and  complete  analyses  of  soils,  and  of  improving  or 
amplifying  some  of  the  methods  given  here,  in  order  to 
perfect  our  scientific  knowledge  of  the  soil,  yet  an  abridg- 
ment of  the  following  course  will  usually  answer  for  all 
practical  purposes  ;  for  such  an  abridged  course,  it  will  be 
sufficient,  for  example,  to  examine  only  that  part  of  the  soil 
that  is  soluble  in  cold  or  hot  concentrated  hydrochloric 
acid,  with  perhaps  the  addition  of  a  mechanical  analysis ; 
but  even  in  this  case,  the  previous  preparation  of  the  soil 
and  of  the  solutions  to  be  analyzed  should  be  made  in 
accordance  with  the  directions  given  below,  at  least  until 
other  methods  become  as  generally  approved  and  adopted." 

PREPARATION  OF  THE  SAMPLE  FOR  ANALYSIS. 

96.  Make  an  excavation  in  the  soil  30-50  cm.  deep,  or 
tlirough  to  the  subsoil,  and  30-50  cm.  square,  with  one 
side  as  nearly  vertical  as  possible,  and  take  a  slice  from 
this  side  of  uniform  thickness  throughout,  weighing  4-5 
kilos.     The  subsoil  lies  below  the  depth  generally  reach- 


96.      PEEPAEATION  OF  THE  SAMPLE  FOE  ANALYSIS.    167 

ed  by  the  plough,  and  is  usually  readily  distinguished 
from  the  upper  soil  by  its  physical  characters,  among 
which  a  ligiiter  color  is  prominent,  owing  to  the  absence 
of  humus.  If  this  subsoil  is  to  be  examined,  a  sample 
of  it  should  be  taken  out  in  the  same  manner  as  directed 
for  the  upper  soil,  to  the  depth  of  about  60  cm.,  and  the 
depth  of  the  cavity  noted. 

The  sample  is  taken,  according  to  the  object  of  the 
analysis,  either 

«,  from  one  or  from  several  spots  in  the  field,  in  order 
to  subject  each  sample  to  a  separate  analysis;  or 

5,  for  an  average  representation  of  the  soil  of  the  whole 
field ;  in  this  case,  several  portions  of  earth  are  taken 
from  points  distributed  in  a  regular  manner  over  the 
field,  all  of  which  are  most  carefully  mixed  together,  and 
4-6  kilos,  of  the  mixture,  free  from  any  large  stones,  are 
preserved  as  the  average  sample. 

If  the  character  of  the  soil  varies  materially  in  differ- 
ent parts  of  the  field,  samples  from  several  spots  should 
be  analyzed  separately. 

A  small  portion  of  the  sample  should  be  put  at  once  in 
a  well-stoppered  bottle  ;  the  remainder  may  be  allowed 
to  become  air-dried,  by  exposing  it  in  a  thin  layer,  in 
summer,  to  the  common  temperature  in  the  shade,  or,  in 
winter,  to  that  of  a  warm  room,  or  a  moderately  warm 
drying-chamber,  heated  to  30°-40°  C. ;  in  either  case  it 
should  be  carefully  protected  from  dust. 

At  the  time  of  taking  the  sample  of  the  soil,  obser- 
vations should  be  made  in  regard  to  the  following  points ; 

a.  The  geognostic  origin  of  the  soil. 

h.  The  nature  of  the  underlying  strata,  to  the  depth 
of  1-2  metres,  if  practicable. 

c.  The  meteorology  of  the  locality — ^l:>y  consulting  me- 
teorological records,  if  possible;  otherwise,  by  the  general 
opinion  of   the  neighborhood;    in  this  connection,  the 


168  §    96.       ANALYSIS    OF    SOILS    AND   EOCKS. 

height  of  the  locality  above  the  level  of  the  sea  should 
be  noted  also. 

d.  The  management  and  rotation  of  crops  in  previous 
years. 

e.  The  character  of  the  customary  manuring. 

/.  The  amount  of  the  crops  removed  in  the  preceding 
year,  and,  if  possible,  the  average  amount  of  each  of  the 
more  important  crops  yielded  by  the  field. 

ff.  The  practical  judgment  of  neighboring  farmers  in 
regard  to  the  field. 

Having  taken  the  sample  to  the  laboratory,  separate 
the  stones  and  larger  pebbles  from  the  finer  parts  by  the 
hand,  or  by  sifting  with  a  very  coarse  sieve,  and  examine 
them  with  reference  to  their  mineralogical  character, 
weight  and  size,  making  note,  in  this  last  respect,  of  the 
number  that  are  as  large  as  the  fist  or  larger,  the  num- 
ber as  large  as  an  egg,  a  walnut,  hazel-nut,  and  pea,. or 
give  the  percentage  of  each  by  weight. 

Pulverize  the  air-dried  soil  in  a  mortar  with  a  wooden 
pestle,  and  separate  the  fine  earth  out  by  a  sieve  with 
meshes  3  mm.  wide  ;  this  sieve  should  have  a  tightly  fit- 
ting cover  of  sheej)-skin  stretched  over  a  hoop,  and  it 
should  be  covered  in  the  same  manner  underneath,  so 
that  no  dust  can  escape  during  the  process  of  sifting. 

Wash  the  pebbles  and  vegetable  fibres  remaining  on 
the  sieve  with  water,  dry  and  weigh  the  residue,  and  ex- 
amine the  pebbles  mineralogically  ;  the  water  with  which 
this  gravel  was  washed  should  be  evaporated  to  dryness 
at  a  temperature  not  exceeding  50°  C.  towards  the  close 
of  the  evaporation,  and  the  residue  mixed  with  what 
passed  through  the  dry  sieve. 

This  sifted  fi?2e  earth  is  reserved  for  all  the  processes 
hereinafter  described,  and  is  kept  in  well-stoppered  bot- 
tles, marked  air-dried  fine  earth. 


§    97.       SILT   ANALYSIS,  1G9 

SILT  ANALYSIS. 

97.  This  air-dried  fine  earth  may  be  separated,  still 
further,  into  portions  of  different  degrees  of  fineness  by 
a  series  of  sieves,  or,  in  a  quicker  and  better  manner,  by 
the  process  of  silt  analysis. 

a.  To  perform  this  with  Kobel's  apparatus  (fig.  6), 
weigh  out  30  grms.  of  the  air-dried  soil,  and  boil  it  for  a 
long  time  with  water,  until  the  lumps  are  completely 
broken  up ;  the  operation  may  be  facilitated  by  gentle 
trituration  with  a  small  pestle  ;  in  the  case  of  very  sandy 
soils,  it  will  be  finished  in  half  an  hour,  but  for  very 
heavy  clay  soils,  two  or  three  hours  may  be  required. 

When  this  is  completed  throw  the  whole  mixture  of 
soil  and  water  on  a  sieve  with  meshes  1  mm.  wide,  rinse 
the  residue  on  the  sieve  well  with  water,  dry  it  at  100°  C, 
and  weigh  it ;  that  which  passes  through  the  sieve,  and 
the  washings,  are  reserved  for  the  silt  analysis  proper. 

The  water  reservoir  of  Nobel's  apparatus  should  hold 
about  10  litres,  and  the  siphon  tube  that  enters  it  should 
extend  down  just  far  enough  to  allow  9  litres  of  vv^ater, 
and  no  more,  to  flow  out ;  the  other  arm  of  the  siphon 
should  be  60  cm.  long,  and  should  have  just  as  large  a 
bore  as  the  tube  of  the  funnel  with  which  it  is  connect- 
ed. The  relative  capacities  of  the  four  silt  funnels,  [N'os. 
1,  2,  3,  and  4,  are  1  :  8  :  26  :  64 ;  together,  they  hold  5 
litres ;  the  mouth  of  the  largest  funnel  where  the  water 
finally  flows  out  of  the  apparatus  should  be  provided 
with  a  tube  drawn  out  to  a  point,  that  is  filed  off  until 
the  orifice  is  of  such  a  size  that,  when  all  the  funnels  are 
filled  with  water,  and  the  connection  with  the  reservoir 
is  made  as  above  directed,  9  litres  will  flow  through  in 
exactly  40  minutes. 

A  large  flask  or  beaker  must  be  provided  to  receive 
the  water  as  it  flows  out  of  the  largest  funnel. 

The  fine  earth,  that  passed  through  the  sieve  with 
8 


170 


97.       ANALYSIS    OF    SOILS    AND    EOCKS. 


meshes  1  mm.  wide,  is  stirred  up  with  water ;  in  case 
there  is  reason  to  suppose  that  funnel  No.  2  will  not  hold 
all  this  mixture  of  soil  and  water,  a  part  of  the  latter, 
holding  only  the  finest  particles  in  suspension,  may  be  put 
in  funnel  No.  3  ;  then  pour  the  rest  of  the  mixture,  just 
after  it  has  been  well  stirred,  into  the  second  funnel, 


Fig.  6. 

while  any  very  coarse  sand  remaining  in  the  beaker  may 
be  rinsed  into  the  first  funnel ;  but  it  is  better  to  put  the 
whole  in  the  second  funnel,  if  possible. 

All  the  funnels  are  then  filled  with  water,  the  connec- 
tions carefully  made  between  them  with  gum  tubing,  and 
the  siphon  leading  from  the  reservoir  is  filled  and  con- 
nected with  the  smallest  funnel.  As  soon  as  9  litres  of 
water  have  passed  through,  the  connection  with  the 
reservoir  is  closed  by  means  of  a  clamp  on  the  gum  tube. 

The  whole  apparatus  is  then  allowed  to  stand  about 
five  hours,  until  the  solid  matters  in  the  funnels  have 


§    97.       SILT   ANALYSIS.  17X 

settled  to  the  bottom ;  then  draw  ojff  the  clear  supernat- 
ant liquid  from  each  funnel  with  a  siphon,  and  transfer 
each  portion  of  the  sediment  to  a  separate  evaporating 
dish,  except  that  the  contents  of  funnels  1  and  2  should  be 
mixed  together;  dry  each  portion  at  125°  C,  and  weigh 
it.  After  this,  ignite  each  one  and  weigh  again,  and. 
thus  determine  the  amount  of  organic  matter  in  it. 

By  this  operation  the  soil  is  separated  into  at  least  five 
portions,  of  diflferent  degrees  of  fineness, 

1.  The  residue  on  the  sieve. 

2.  The  contents  of  funnel  No.  2. 

3.  "  "        "         "      No.  3.  ^ 

4.  "  "         '^         "       No.  4. 

5.  The  sediment  deposited  from  the  water  that  flowed 
through  the  whole  apparatus,  and  the  still  finer  portions 
remaining  suspended  in  the  water  even  after  several 
hours.  These  two  may  be  separately  determined,  if  it  is 
desired,  by  collecting,  drying,  and  weighing  the  sediment 
that  is  deposited  after  several  hours,  and  then  estimating 
the  still  finer  portion  that  remains  in  suspension,  together 
with  the  hygroscopic  water  of  the  soil,  by  the  difierence 
between  the  30  grms.  of  soil  taken  originally,  and  the 
sum  of  these  five  residues ;  then  on  subtracting  from 
this  remainder  the  hygroscopic  water,  as  determined  in 
another  portion  of  the  soil,  we  have  the  weight  of  the 
sixth  portion ;  or,  the  fifth  and  sixth  may  be  estimated 
together,  in  a  similar  manner,  and  without  collecting  the 
sediment  deposited  in  the  beaker. 

To  clarify  this  liquid  more  speedily,  A.  Mtiller  {Jour- 
nal far  PraJct.  Chemie,  95,92;  Fresenius's  Zeitschrift, 
5,  243)  recommends  the  following  process.  Prepare  a 
solution  of  an  ammoniacal  soap,  with  the  aid  of  stearic 
acid,  ammonia,  and  alcohol,  add  it  to  the  turbid  liquid 
until  the  mixture  gives  considerable  foam  when  violently 
agitated,  then  acetic  acid  until  the  reaction  of  the  liquid 
is  decidedly  acid,  and  stir  or  shake  the  whole  vigorously; 


172 


§    97.       ANALYSIS    OF    SOILS    AND    EOCKS. 


the  fatty  acid  that  is  set  free  by  the  acetic  acid  envelopes 
the  fine  particles  of  earth,  and  the  flocculent  sediment 
can  be  filtered  out  without  difficulty.  The  fatty  acid 
may  then  be  removed  from  the  other  solid  matters,  with 
which  it  is  mixed,  by  ignition,  or  by  treatment  with  alco- 
hol, and  the  residue  will  represent  the  finest  portion  of 
the  soil. 

h.  The  following  method  of  silt  analysis,  by  Dietrich 
{Fresenius' s  Zeitschrift,  5,  296)  is  preferred  by  some  to 
that  described  above ;  the  apparatus  may  be  easily  con- 
structed out  of  the  ordinary  stock  of  the  laboratory. 

The  water  is  caused  to  flow,  under  a  constant  pressure 
of  1  metre,  through  a  series  of  four  tubes  of  different 
sizes,  and  inclined  to  the  horizon  at  different  angles,  as 
follows  ; 


Number 
ilietube. 

Length. 

Diameter. 

Angle  between  its  axis 

and  a 

hoj'izontal  plane. 

1 
2 
3 
4 

17  cm. 
34    " 

51     " 
68    " 

2.8  cm. 
4       " 
5.2    « 
6.4    " 

90° 
67.5° 
45° 
22.5° 

Each  tube  is  drawn  out  at  one  end  so  that  a  rubber 
tube  can  be  attached  to  it,  while  the  other  end  is  closed 
with  a  rubber  cork,  through  which  a  short  glass  tube 
passes ;  each  tube  is  connected  with  the  next  larger  one 
by  a  rubber  tube  passing  from  the  corked  end  of  the 
former,  which  is  at  the  same  time  the  upper  end,  to  the 
lower,  tapering  end  of  the  latter,  and  the  water  flows 
from  the  upper  end  of  one  tube  to  the  lower  end  of  the 
next  larger  one.  Each  rubber  tube  is  cut  in  the  middle 
of  its  length,  and  the  cut  ends  are  connected  together  by 
a  short  glass  tube  ;  each  rubber  tube  also  has  a  clamp  on 
it,  by  means  of  which  the  flow  of  the  water  can  be  regu- 
lated. The  30  grms.  of  soil,  prepared  as  for  the  silt 
analysis  with  Nobel's  apparatus,  are  put   in    the  first 


§    98.      THE    CHEMICAL   ANALYSIS.  173 

tube,  and  the  flow  of  the  water  through  the  apparatus  is 
continued  until  it  comes  away  from  the  last  tube  tolera- 
bly clear.  The  remainder  of  the  operation  is  conducted 
in  the  same  manner  as  when  using  Nobel's  apparatus. 

THE  CHEMICAL  ANALYSIS. 

98.  The  soil  for  tliis  analysis  should  always  be  taken 
in  its  natural,  air-dried  condition,  without  previous  igni- 
tion to  expel  the  organic  matter,  since  the  ignition  may 
at  the  same  time  alter  very  materially  the  effect  of  the 
agents  employed  for  solution. 

a.   Hyi^roscopic  water  and  other  Tolatilc  matter.— 

Determine  the  amount  of  water  expelled  at  100°  C.  from 
10  grms.  of  soil  (§  90),  and  then  ignite  the  dried  residue 
to  determine  water  chemically  combined  or  otherwise  re- 
tained at  100°  C,  humus,  and  volatile  mineral  substances 
(§  91) ;  the  ignited  residue  should  be  treated  with  am- 
monic  carbonate,  if  a  qualitative  test  reveals  the  presence 
of  carbonic  acid  in  the  soil,  and  carbonic  acid  should  be 
determined  in  the  ash  (§  91,  d). 

A.  Midler  allows  but  little  value  to  this  estimation  of 
water  of  hydrates  in  the  soil,  and  organic  matter,  even 
when  combined  with  the  determination  of  carbonic  acid 
both  before  and  after  ignition. 

h.  Estimate  carbonic  acid  in  5-10  grms.  of  soil,  dried 
at  100°  (§  60,  h). 

c.  Determine  the  total  nitrogen  in  5-10  grms  of  soil, 
dried  at  100°,  by  combustion  with  soda-lime  (§  85). 

A,  Miiller  mixes  the  soil  with  about  an  equal  quantity 
of  caustic  jDotash  or  soda,  instead  of  with  soda-lime,  but 
fills  the  rest  of  the  tube  with  soda-lime  in  the  usual  man- 
ner ;  in  this  way  he  avoids  the  use  of  very  long  combus- 
tion-tubes. 

If  much  nitrate  is  present  in  the  soil,  and  but  little  hu- 


174  §    99.      ANALYSIS    OF   SOILS   AND   EOCKS. 

mus,  it  will  be  safer  to  add  0.2-0.4  grm.  of  pure  cane 
sugar  to  the  sample  in  which  nitrogen  is  determined; 
otherwise  some  of  the  nitrogen  may  escape  conversion 
into  ammonia;  a  small  portion  of  the  sugar  should  be 
ignited  by  itself  with  soda-lime,  cither  to  determine  the 
amount  of  nitrogen  it  contains,  or  to  be  sure  of  its  free- 
dom from  that  imj)urity. 

d.  In  order  to  determine  the  solubility  of  the  various 
elements  of  plant-food  in  the  soil,  it  is  necessary  to  treat 
it  successively  with  different  solvents,  and  with  these  of 
various  degrees  of  strength ;  in  order  that  the  results  ob- 
tained by  different  chemists  may  be  compared  with  each 
other,  it  is  absolutely  essential  that  these  solvents  should 
be  applied  in  the  same  order  and  in  the  same  manner. 

A  convenient  and  useful  order  is  the  following : 

1.  Cold,  distilled  water,  '|^  saturated  Avith  carbonic 
acid. 

2.  Cold  concentrated  liydrochloric  acid  (Sjx  Gr.  —  1.15). 

3.  Boiling  concentrated  hydrochloric  acid  of  the  same 
strength. 

4.  Hot  concentrated  sulphuric  acid. 

5.  Hydrofluoric  acid. 

The  solutions  obtained  by  the  treatment  of  the  soil 
with  these  agents  in  succession  will  be  found  to  differ 
very  much  in  their  composition,  and  to  yield  data  for 
very  interesting  deductions  in  regard  to  its  natural  fer- 
tility. 

Unless,  however,  a  very  complete  analysis  is  desired, 
but  one  of  these  solutions,  viz.,  that  in  cold  concentrated 
hydrochloric  acid,  need  be  examined  quantitatively  ;  next 
to  this,  the  solution  in  hot  hydrochloric  acid  is  of  great- 
est importance ;  we  shall,  therefore,  consider  the  treat- 
ment of  these  first  of  all. 

Solution  in  Cold   Concentrated   Hydrochloric  Acid. 

99.  Put  450   grms.  of  air-dried  soil  in  a  large,  glass- 


§    99.       THE    CHEMICAL   ANALYSIS.  175 

stoppered  bottle,  and  pour  over  it  1500  c.c.  of  pure  con- 
centrated hydrochloric  acid  (Sp.  Gr.  =  1.15),  and  shake 
the  mixture  frequently  during  a  digestion  of  48  hours,  at 
the  common  temperature  of  the  working-room ;  then  let 
it  stand  until  1000  c.c.  of  at  least  a  tolerably  clear  liquid 
can  be  poured  off  or  drawn  oif  with  a  siphon ;  this  quan- 
tity of  the  solution  represents  ^\^oi  450  grms.,  or  300 
grms.  of  the  soil  taken  for  the  analysis ;  dilute  the  liquid 
with  its  volume  of  water,  and  filter  it. 

If  the  soil  contains  a  very  large  proportion  of  calcic 
carbonate,  the  cold  acid  solution  may  be  filtered  off  after 
dilution  with  its  volume  of  water,  and  the  whole  quan- 
tity used  for  the  analysis,  representing  the  whole  of  the 
soil  taken ;  in  this  case,  wash  the  insoluble  residue  care- 
fully first  with  cold  and  then  with  hot  Avater,  dry  it  at 
100°  C,  and  weigh,  to  deteimine  the  proportion  of  the 
soil  insoluble  in  cold  acid;  5-10  grms.  of  this  may  be 
ignited,  to  determine  the  organic  matter  in  the  insolu- 
ble portion ;  then  reserve  the  rest  for  treatment  with  so- 
dic  carbonate,  to  determine  soluble  silica,  and  with  hot 
concentrated  acid. 

Evaporate  the  solution  to  dryness  with  the  addition  of 
a  few  drops  of  concentrated  nitric  acid  towards  the  close 
of  the  evaporation,  to  oxidize  ferrous  oxide  and  organic 
matters,  and  eliminate  silica  (§  58,  a,  1). 

Dilute  the  filtrate  from  the  silica  to  1000  c.c,  and 
analyze  it  according  to  Scheme  II.,  §  94,  taking  400  c.c. 
for  a,  200  for  b,  and  400  for  c. 

In  ^,  a  slight  insoluble  residue  often  remains,  on  dis- 
solving the  precipitate  by  sodic  acetate  in  hydrochloric 
acid ;  in  this  case,  dry  the  residue,  ignite  it  and  the  filter, 
digest  the  ash  a  long  time  with  concentrated  hydroclilodc 
acid,  filter  if  necessary,  and  add  the  filtrate  to  the  re- 
mainder of  the  solution  of  the  precipitate  by  sodic  ace- 
tate in  hydrochloric  acid,  ignite  and  weigh  the  insoluble 
residue,  if  there  is  any,  and  add  it  to  the  silicic  acid. 


176  §    99.      ANALYSIS    OF    SOILS   AXD    ROCKS. 

If  the  soil  is  very  rich  in  organic  matter,  it  will  be  bet- 
ter to  treat  500  c.c.  of  the  solution  with  sodic  carbonate 
and  potassic  nitrate,  or  Avith  chlorine,  as  directed  in 
§  93,  A,  and  use  ^j^  of  the  solution  finally  obtained  for  J, 
omitting,  of  course,  the  determination  of  the  alkalies 
in  this  portion  of  the  solution  unless  the  oxidation  was 
effected  with  chlorine,  and  ^1^  for  c. 

Sometimes,  however,  when  there  is  not  a  very  large 
proportion  of  organic  matter  present,  and  the  above 
treatment  for  oxidation  is  not  followed,  traces  of  organic 
matter  are  contained  in  the  solution  of  ferric  oxide  ob- 
tained in  J,  for  estimation  with  permanganate;  where 
great  accuracy  is  required  therefore,  it  would  be  well, 
after  having  titrated  the  ferric  solution  once,  to  reconvert 
the  ferric  oxide  into  ferrous,  with  zinc  or  sulphurous 
acid,  titrate  the  solution  again,  and  to  repeat  this  until 
a  constant  result  is  obtained.  The  same  mode  of  pro- 
cedure should  be  followed,  also,  in  estimating  the  strength 
of  the  permanganic  solution. 

In  accurate  soil  analyses,  the  phosphoric  acid  should  be 
estimated  twice. 

In  a  complete  soil  analysis,  it  is  desirable  to  determine 
the  silicic  acid,  which,  after  treatment  of  tlie  soil  with 
cold  concentrated  hydrochloric  acid,  is  soluble  in  a  con- 
centrated solution  of  sodic  carbonate. 

For  this  purpose,  take  5-10  grms.  of  the  residue  that 
was  insoluble  in  the  acid,  in  case  of  a  soil  rich  in  carbon- 
ates ;  or,  digest  25  grms.  of  the  air-dried  soil  with  three 
times  the  quantity  of  cold  concentrated  acid,  48  hours  in 
the  cold,  filter,  and  Avash  the  contents  of  the  filter  perse- 
veringly,  first  Avith  cold  and  afterwards  Avitli  hot  water, 
and  use  this  residue. 

Boil  this  insoluble  substance  and  also  an  equal  amount 
of  the  original  air-dried  soil,  Avith  sodic  carbonate,  in  tlio 
manner  described  for  the  separation  of  sand  and  silica 
(§  58,  a,  2).      The  difference  between  the  amounts  of 


§    100.       THE    CHEMICAL   AXALTSIS.  177 

silicic  acid  dissolved  in  the  two  cases  furnishes  a  means 
of  estimating  the  extent  of  the  action  of  the  cold  acid  on 
the  silicates  in  the  soil. 
Treatment  of  the  Soil  with  Carbonated  Water. 
100.  To  determine  only  the  total  quantity  of  organic 
and  inorganic  matters  in  the  soil,  soluble  in  water  con- 
taining carbonic  acid  in  solution,  without  reference  to  the 
composition  of  the  dissolved  substances,  put  500  gims. 
of  air-dried  soil  in  a  flask  that  can  be  well  stoppered,  and 
l^our  over  it  as  much  carbonated  water  as  will  make,  to- 
gether with  the  hygroscopic  water  in  the  soil,  2000  c.c. 
The  water  should  be  ^|^  saturated  with  carbonic  acid,  by 
saturating  500  c.c.  at  the  common  temperature  and  press- 
ure, and  mixing  this  with  1500  c.c.  of  pure  water.  When 
thus  pre2:)ared,  the  water  is  more  nearly  like  that  in  the 
soil,  whose  action  we  wish  to  imitate. 

Leave  the  soil  and  water  in  contact  with  each  other 
three  days,  with  frequent  agitation,  then  pour  off  1000 
c.c.  of  as  clear  a  liquid  as  possible,  representing  250  grms. 
of  soil,  and  filter  through  a  double  filter,  while  keeping 
the  funnel  w^ell  covered  with  a  glass  plate.  Evaporate 
the  clear  filtrate  to  dryness  at  a  temperature  below  boil- 
ing, dry  the  residue  at  125°  C,  weigh,  ignite,  and  after 
treatment  several  times  with  ammonic  carbonate  and 
gentle  ignition,  weigh  again.  The  difference  between  the 
two  weights  gives  the  amount  of  organic  matter  dissolved 
by  tlie  carbonated  water. 

The  carbonic  acid  is  determined  in  the  ignited  residue, 
as  in  §  60. 

If  a  detailed  chemical  examination  of  the  solution  in 
carbonated  water  is  to  be  made,  at  least  1500  grms.  of 
soil  must  be  taken  instead  of  500,  and  the  water  in  the 
same  proportion.  After  three  days,  pour  oif  4000  c.c.  of 
the  clear  supernatant  liquid,  representing  two-thirds  of 
the  soil,  let  it  stand  24  hours  in  well-closed  and  full 
bottles,  filter  as  directed  above,  and  without  disturbing 
8- 


178  §    100.      ANALYSIS    OF    SOILS    AND   KOCKS. 

the  sediment  at  the  bottom  of  the  bottles.  If  a  clear 
filtrate  is  not  obtamed  in  this  way,  it  must  be  evaporated 
down  to  400  or  500  c.c.,  just  barely  supersaturated  with 
hydrochloric  acid  while  still  hot,  and  then  filtered  again. 

Evaporate  the  solution  to  dryness,  with  the  addition 
of  a  few  drops  of  nitric  acid  towards  the  close  of  the 
evaporation,  to  peroxidize  the  iron  and  destroy  organic 
matter,  and  eliminate  silicic  acid.     (§  58,  a^  1.) 

Treat  the  filtrate  from  the  silica  as  in  Scheme  I.,  §  94. 
Alumina,  ferric  oxide,  and  phosphoric  acid,  are  usually 
present,  however,  in  such  small  quantities  in  this  solution, 
that  it  is  hardly  worth  while  to  determine  at  least  the 
first  two. 

Interesting  results  may  be  obtained  by  the  successive 
treatment  of  the  same  portion  of  soil  with  carbonated 
water,  and  a  chemical  examination  of  each  solution;  the 
proportion  may  thus  be  learned  in  which  the  more  im- 
portant elements  of  plant-food  are  taken  up  by  the  suc- 
cessive aqueous  extracts,  and  data  are  obtained  for  esti- 
mating, not  only  the  general  richness  of  the  soil  in 
valuable  elements  of  plant-food,  such  as  phosphoric  acid 
and  potassa,  but  also  the  relation  between  the  immediate 
fertility  of  the   soil  and  the  durability  of  its  fruitfulness. 

A  very  great  decrease  in  the  amount  of  the  elements 
of  plant-food  in  the  second  and  third  extracts,  as  com- 
pared with  the  first,  would  indicate  that  the  fertility  of 
the  soil  would  be  very  much  lessened  in  a  single  season. 
If,  on  the  contrary,  there  is  but  little  diminution  observ- 
ed even  in  the  fifth  extract,  the  power  of  the  soil  to 
produce  crops  will  probably  remain  about  the  same,  year 
after  year,  for  a  long  time. 

To  obtain  these  successive  extracts,  replace  the  4000 
c.c.  that  were  poured  off"  for  the  first  extract,  by  an  equal 
quantity  of  fresh  Avater  \  saturated  witli  carbonic  acid  as 
before,  let  stand  three  days  with  frequent  shaking,  pour 


§    101.       THE    CHEMICAL   ANALYSIS.  179 

off  4000  c.c.  again,  and  repeat  this  operation  for  the  third 
and  fourth  time,  or  even  more,  as  may  be  desired. 

Ulbricht  found,  that  after  the  third  or  fourth  extract, 
the  amount  dissolved,  at  least  by  distilled  water  free  from 
carbonic  acid,  remained  nearly  constant,  and  that  the 
composition  of  one  of  these  last  extracts  would  furnish 
the  means  for  estimating  the  lasting  fertility  of  the  soil. 

It  will  usually  answer  to  examine  quantitatively  the 
first,  third,  fifth,  and  seventh  extracts  by  carbonated 
water. 

Interesting  results  may  be  obtained  also  by  treating 
the  soil  in  the  manner  above  directed  with  water  contain- 
ing 0.5  gmi.  of  ammonic  chloride  in  the  litre,  in  addition 
to  the  usual  charge  of  carbonic  acid. 

Treatment  of  the  Soil  with  Hot  Concentrated 
Hydrochloric  Acid. 

101.  If  the  soil  contained  a  very  large  proportion  of 
calcic  carbonate,  the  residue  insoluble  in  cold  acid  may 
be  treated  with  hot  acid ;  otherwise  the  separation  of  the 
insoluble  from  the  soluble  part  by  filtration  is  too  diffi- 
cult, and  it  is  better  to  begin  with  a  fresh  portion  of  soil. 
Pour  300  c.c.  of  concentrated  acid  over  150  grms.  of  the 
air-dried  soil,  or  over  the  whole  of  the  residue  insoluble 
in  cold  acid  in  case  carbonates  were  present  in  large 
quantity,  in  a  large  flask,  add  a  few  drops  of  nitric  acid 
to  oxidize  slimy  matters  that  might  obstruct  the  filter, 
heat  to  boiling  w^th  constant  agitation,  and  continue  to 
boil  gently  for  exactly  an  hour ;  dilute  the  solution  with 
twice  its  volume  of  water,  and,  after  letting  the  mixture 
stand  quietly  for  a  short  time,  decant  the  liquid  into  a 
filter  that  is  double  at  the  bottom ;  treat  the  insoluble 
residue  in  the  flask  at  least  three  times  with  boiling  wa- 
ter, filter  the  liquid  each  time,  and  finally  bring  the  resi- 
due itself  on  the  filter,  and  wash  it  thoroughly  with  boil- 
ing water. 

Evaporate  the  solution  and  washings  to  dryness,  with 


180  §    102.       AN-ALYSIS    OF    SOILS    AND    EOCKS. 

the  addition  of  a  few  drops  of  nitric  acid  towards  the 
close  of  the  evaporation,  to  destroy  organic  matter  and 
oxidize  ferrous  salts,  and  eliminate  silica.     (§  58,  a,  1.) 

Examine  the  filtrate  from  the  silica,  which  is  to  be 
made  up  to  1000  c.c.  and  well  mixed,  according  to 
Scheme  II.,  §  94. 

Or,  in  order  to  have  a  larger  quantity  of  solution  for 
the  determination  of  phosphoric  and  sulphuric  acids,  the 
analysis  may  be  performed  by  Scheme  I.,  in  which  a  and 
h  may  be  united,  and  the  sulphuric  acid  determined  as 
usual,  while  half  the  filtrate  from  the  j^recipitate  by 
ammonia  for  phosphoric  acid  will  answer  for  the  determi- 
nation of  the  alkalies. 

Examination  of  the  Residue  Insoluble  in  Hot  Hydro- 
chloric Acid. 

102.  Dry  it,  and  remove  it  from  the  filter  as  completely 
as  possible,  burn  the  latter,  and  weigh  ash  and  residue, 
and  separate  the  carefully  prepared  mixture  of  the  two 
into  three  accurately  weighed  portions  of  10  grms.  (a), 
10-15  grms.  (^),  and  15-20  grms.  (e). 

a.  Ignite  this  portion,  to  determine  the  amount  of  min- 
eral matter  insoluble  in  the  hot  acid. 

b.  In  this  portion  determine  the  silica  soluble  in  car- 
bonated alkali.     (§  58,  c/,  2.) 

c.  Pour  five  times  its  weight  of  concentrated  sulphuric 
acid  over  this  portion,  heat  until  the  excess  of  acid  is 
removed,  and  the  residue  forms  a  light,  dry  powder ;  the 
evaporation  of  the  acid  should  be  performed  slowly  and 
with  constant  stirring,  and  should  require  from  six  to 
eight  hours.  Moisten  the  residue  freely  with  concentrat- 
ed hydrochloric  acid,  remove  this  acid  by  long  heating  in 
the  water-bath,  boil  the  residue  repeatedly  Avith  water  to 
which  a  little  hydrochloric  acid  has  been  added,  filter,  and 
wash  the  insoluble  residue  carefully. 

Examine  the  solutions  and  washings,  after  concentra- 
tion, according  to  Scheme  VII.,  §  94. 


§    103.       THE    CHEMICAL   ANALYSIS.  181 

The  amount  of  lime  is  usually  small.  Wolff  directs 
that  the  filtrate  from  the  precipitate  of  calcic  oxalate  be 
evaporated  to  dryness,  the  residue  ignited  gently  in  a 
platinum  dish,  to  expel  ammoniacal  salts,  dissolved  in  di- 
lute acid,  and  any  silicic  acid  that  may  appear  as  an  in- 
soluble residue  be  filtered  out;  then  add  ammonia  in 
slight  excess  to  the  filtrate,  filter  out  any  flocculent  pre- 
cipitate of  alumina  that  may  also  appear,  and  finally  de- 
termine sulphuric  acid  with  baric  chloride. 

This  treatment  of  the  soil  with  sulphuric  acid  serves 
to  determine  the  amount  of  clay  in  it,  and  Wolff  has 
found,  by  repeated  trials,  that  the  clay  is  completely 
decomposed  if  the  operation  is  carefully  perfonned.  He 
gives  importance  to  the  determination,  for  it  furnishes  data 
for  controlling  the  results  obtained  by  the  silt  analysis, 
and'  because  it  gives  valuable  information  in  regard  to 
the  degree  of  insolubility  of  the  other  constituents  of  the 
soil,  and  particularly  the  alkalies. 

The  process  is  a  good  connecting  link  between  the 
treatment  with  hydrochloric  acid  on  the  one  hand  and 
hydrofluoric  acid  on  the  other. 

Examination  of  tlie  Residue  Undecomposed  by  Sul- 
phuric Acid. 

103.  a.  Dry  this  residue  at  100°,  burn  the  filter  by  it- 
self, and  weigh  the  ash  and  residue ;  mix  them  well  to- 
gether, and,  in  half  of  the  mixture,  determine  silica  solu- 
ble in  alkaline  carbonates.  (§  58,  a,  2.)  The  silicic  acid 
thus  found,  together  with  the  small  quantity  in  the 
hydrochloric  and  sulphuric  acid  solutions,  gives,  in  con- 
nection with  the  alumina  found  in  the  same  solutions, 
an  approximate  estimate  of  the  pure  anhydrous  clay  in 
the  soil.  This  amount  of  silicic  acid  is,  in  general,  too 
large  in  proportion  to  that  of  the  alumina,  for  a  part  of 
it  was  combined  with  ferric  oxide,  lime,  etc. 

The  clay  that  is  decomposed  by  the  sulphuric  acid 


182  §    103.       ANALYSIS    OF    SOILS    AND    ROCKS. 

alone  is  very  nearly  pure,  while  it  is  that  which  is  dissolved 
by  the  hydrochloric  acid  that  contains  too  much  silica. 

Ignite  the  other  half  of  the  residue,  to  determine  the 
amount  of  mineral  matters  insoluble  after  treatment  with 
sulphuric  acid. 

Pulverize  the  ignited  mass  very  finely  in  an  agate 
mortar,  separate  the  finer  from  the  coarser  portions  by 
levigation  (§  36)  with  distilled  water,  pulverize  the  coarse 
part  again,  and  repeat  the  levigation ;  when  in  this  way 
the  whole  is  reduced  to  the  finest  possible  powder,  eva2> 
orate  the  water  to  dryness  with  the  matters  in  suspension 
in  it,  weigh  out  3-4  grms.  of  the  well-dried  residue,  and 
treat  it  with  hydrofluoric  acid  or  amnionic  fluoride 
(§58,c). 

Examine  the  solution  thus  obtained  according  to  Scheme 
VII.,  §  94.  The  determination  of  ferric  oxide  will,  how- 
ever, be  necessary,  only  when  the  precipitate  by  ammonia 
is  yellowish  or  reddish. 

If,  as  is  usually  the  case,  the  solution  is  found  to  con- 
tain only  traces  of  lime  and  magnesia,  the  amount  of 
feldspathic  minerals  and  of  pure  quartz  sand  in  this  in- 
soluble part  of  the  soil  can  be  estimated  from  the  amount 
of  alkalies  found ;  and,  from  the  amount  of  aluminic  sili- 
cate, it  may  be  judged  how  perfectly  the  clay  was  de- 
composed by  the  previous  treatment  with  sulphuric  acid. 

h.  According  to  A.  Miiller,  the  relative  proportion  of 
silicates  and  quartz  sand  in  a  soil  can  be  determined  with 
accuracy  by  digestion  with  phosphoric  acid  at  a  certain 
temperature;  all  the  silicates  are  decomposed  by  this 
treatment,  and  the  silica  is  separated  in  a  gelatinous  form 
while  the  quartz  sand  remains  unchanged. 

For  this  purpose  a  syruj^y  acid  is  required  containing 
40-45°l  g  of  anhydrous  acid ;  it  may  be  obtained  by  con- 
centrating the  commercial  acid. 

The  insoluble  residue  to  be  treated  with  the  acid  must 
be  very  finely  pulverized,  but  it  need  not  be  levigated ; 


§    104.       MISCELLANEOUS    ESTIMATIONS.  183 

the  amount  of  pliosplioric  acid  required  depends  upon 
the  amount  of  silicates  present,  and  at  least  15-20  grms. 
should  be  taken  for  0.5-1.0  grm.  of  the  substance.  The 
mixture  is  heated  in  a  platinum  dish  in  an  air-bath  to 
190-200°  C,  and  digested  five  or  six  hours  at  this  temper- 
ature, while  constantly  stirred  with  a  platinum  spatula. 
The  resulting  mass  is  boiled  several  times  with  water 
containing  1"!  ^  of  sodic  hydrate,  the  clear  liquid  decanted 
off  each  time,  and  the  sandy  residue  itself  is  finally 
brought  on  the  filter  and  washed  carefully  with  acid,  alkali, 
acid  again,  and  finally  with  water,  ignited  and  weighed. 

MISCELLANEOUS    ESTIMATIONS. 

104.  a.  IlumuSo — Weigh  out  5-10  grms:  of  the  air- 
dried  soil,  pour  over  it  200  c.c.  of  water  in  the  flask  of 
the  apparatus  for  determining  carbonic  acid  (§  60,  b),  and 
30  c.c.  of  concentrated  sulphuric  acid;  shake  the  mixture 
gently  and  let  it  stand  some  time  until  it  has  become 
quite  cold,  meanwhile  changing  the  air  in  the  flask  sev- 
eral times  by  blowing  into  it,  so  as  to  remove  all  the  car- 
bonic acid  expelled  from  carbonates  in  the  soil  by  the 
stronger  acid. 

Now,  put  7-8  grms.  of  coarsely  pulverized  potassic  di- 
chromate  in  the  flask  (or,  better  still,  5  grms.  of  pure 
chromic  acid),  or  such  a  quantity  that  there  will  be  17 
parts  of  chromic  acid  for  one  of  organic  matter,  as  de- 
termined, ap2)roximately  at  least,  in  the  beginning,  by  ig- 
nition (§  98,  a) ;  apply  a  gentle  heat,  and  proceed  to 
collect  the  carbonic  acid  evolved  as  in  §  60,  i,  except  that 
a  U  tube  filled  with  iron  wire  should  be  interposed  be- 
tween the  flask  and  the  U  tube  ff,  to  absorb  chlorine, 
and  except,  also,  that  no  nitric  acid  need  be  added  to 
the  substance.  Towards  the  close  of  the  operation,  boil 
the  contents  of  the  flask  five  minutes,  and  finally  draw 
air  throusfh  in  the  usual  manner.     The  carbonic  acid  is 


184  §    104.       ANALYSIS    OF    SOILS    AND    EOCKS. 

set  free  by  the  oxidation  of  the  humus  by  the  chromic 
acid. 

Since  humus  contains  on  an  average  SS"!  ^  of  carbon, 
multiply  the  quantity  of  carbonic  acid  found  by  0.4702, 
for  the  amount  of  humus. 

The  difference  between  the  sum  of  the  humus  and  the 
nitrogen  and  the  total  loss  suffered  on  ignition  (§  98) 
gives  the  amount  of  water,  chemically  combined  or  other- 
wise retained  at  100°  C. 

Some  information  in  regard  to  the  nature  of  the  or- 
ganic matter,  and  the  extent  to  which  decay  has  pro- 
gressed, may  be  obtained  by  comparing  the  amount  of 
humus,  or  of  the  carbon  in  it,  with  that  of  the  nitrogen, 
by  a  microscopic  examination  of  the  various  products 
of  the  silt  analysis  and  by  the  loss  suffered  by  these  c:a 
ignition,  and  also  by  the  following  tests. 

1.  The  reaction  of  the  soil  or  of  the  humus  contained 
in  it,  which  is  tested  by  allowing  moistened  lumps  of  the 
soil  to  remain  in  contact  with  carefully  prepared  blue  and 
red  litmus-paper ;  a  change  from  blue  to  red  may  be 
caused  by  carbonic  acid,  but,  if  the  red  color  remains 
after  the  paper  is  thoroughly  dry,  the  change  was  due  to 
acids  of  the  humus,  unless  the  soil  gives  the  same  reaction 
after  gentle  ignition,  in  which  case  it  may  have  been 
caused  by  acid  sulphates. 

2.  Mix  100  grms.  of  the  soil  with  200  c.c.  of  a  stand- 
ard ammoniacal  solution  of  calcic  nitrate  of  such  a 
strength  that  200  c.c.  contain  1  grm.  of  lime,  and  an 
amount  of  ammonia  chemically  equivalent  to  this  amount 
of  lime.  After  frequent  shaking  of  the  mixture  in  the 
course  of  24  hours,  filter,  and  determine  lime  in  a  measur- 
ed quantity  of  the  filtrate ;  the  lime  that  is  missing  was, 
according  to  Knop,  absorbed  by  the  humus,  and  may  be 
taken  as  an  approximate  measure  of  the  amount  of  the 
same. 

3.  To  determine  the  amount  of  organic  matter,  mainly 


§    104.       MISCELLANEOUS    ESTIMATIONS.  185 

in  the  form  of  humus,  that  is  extracted  from  the  soil  by- 
water  or  alkaline  solutions,  the  following  method  is  given 
by  Schulze.  Boil  10  grins,  of  soil  15  minutes  with  200 
c.c.  of  a  solution  containing  0.5"  |„  of  potassa,  bring  the 
volume  of  the  whole  to  250  c.c,  pour  the  liquid  on  a  dry- 
filter,  or  through  dry,  fine-grained  sand  with  which  the 
throat  of  the  funnel  is  stopj^ed ;  put  4-6  c.c.  of  the  filtrate 
in  a  flask^f  about  200  c.c.  capacity,  dilute  with  about  100 
c.c.  of  water,  and  determine  organic  matter  in  100  c.c.  of 
this  solution  by  means  of  standard  solutions  of  potassic 
permanganate  and  oxalic  acid  (§  91,  e). 

h.  Ammonia* — The  amount  of  ammonia  existing  al- 
ready formed  in  soils  is  nearly  always  very  small,  since  it 
is  so  readily  converted  into  nitrates. 

To  determine  it  by  Schlossing's  method  (§  47,  b),  treat 
50  grms.  of  soil  with  40  c.c.  of  a  cold  saturated  solution 
of  sodic  hydrate.  After  48  hours  remove  the  acid  from 
under  the  bell-jar,  titrate  it,  stir  the  soil  in  the  watch- 
glass,  put  another  measured  portion  of  acid  in  the  projDcr 
vessel,  and,  after  48  hours,  titrate  this  also  with  the 
standard  sodic  solution.  If  no  more  ammonia  was  set 
free  during  the  second  period,  the  first  determination 
may  be  considered ,  snfiicient ;  if  more  was  set  free,  it 
should  be  added  to  the  first  quantity  found,  and  a  new 
portion  of  acid  should  be  put  in,  in  the  place  of  the  last, 
and  tested  after  48  hours. 

It  may  also  be  desirable  to  estimate  the  ammonia  that 
is  set  free  on  heating  the  soil  with  magnesia.  Pour  500 
c.c.  of  water  containing  5  grms.  of  freshly  ignited  mag- 
nesia over  100  grms.  of  soil,  mix  the  whole  well  together, 
and  proceed  to  distil  off  the  ammonia  (§  47,  c). 

Probably  no  great  reliance  can  be  placed  on  any  method 
of  determining  ammonia  in  soils. 

c.  Nitric  acid. — The  accurate  determination  of  nitric 
acid  is  not  difficult,  as  the  nitrates  are  so  easily  extracted 
from  the  soil  by  water. 


186  §    104.       ANALYSIS    OF    SOILS    AND    ROCKS. 

To  1000  grms.  of  the  soil  add  water  enough  to  make 
2000  c.c.  with  that  already  in  the  soil,  shake  the  mixture 
frequently  in  the  course  of  48  hours,  decant  and  filter 
1000  c.c.  through  a  dry  filter,  add  some  sodic  carbonate 
to  the  filtrate,  evaporate  the  solution  to  a  small  bulk  on 
the  water-bath,  and  divide  the  residue  into  two  equal 
parts.  Determine  nitric  acid  in  each  portion,  represent- 
ing 250  grms.  of  soil,  in  the  usual  manner  (§  62  ci). 

d.  Chlorine* — To  determine  this,  add  enough  water  to 
300  grms.  of  the  air-dried  soil  to  make  900  c.c.  with  what 
is  already  contained  in  it,  shake  the  mixture  frequently 
in  the  course  of  48.  hours,  decant  and  filter  450  c.c.  of  the 
liquid,  add  a  little  sodic  carbonate  to  the  filtrate,  evapo- 
rate to  about  200  c.c,  filter  again,  supersaturate  the  fil- 
trate, which  represents  150  grms.  of  soil,  with  nitric  acid, 
and  precipitate  the  chlorine  in  the  acid  solution  with 
argentic  nitrate  (§  63).  Treat  the  precipitate  as  one  pro- 
duced in  the  presence  of  organic  matter. 

e.  Sulphur. — It  often  happens  that  a  much  larger 
amount  of  sulphuric  acid  is  found  in  the  soil  after  ignition 
than  before,  indicating  that  a  notable  quantity  of  sul- 
phur exists  there  as  sulphuret,  or  in  some  organic  combi- 
nation. To  determine  the  total  amount  of  sulphur  in  the 
soil,  mix  with  50  grms.  of  it,  1-2  grms.  of  pure  saltpetre, 
moisten  the  mixture  in  a  platinum  dish  with  a  solution  of 
pure  potassic  or  sodic  hydrate,  free  particularly  from  sul- 
phates, dry,  and  heat  gradually  to  a  red  heat ;  when  the 
mass  is  cool,  boil  it  with  dilute  hydrochloric  acid  to 
which  a  little  nitric  has  been  added,  evaporate  to  dryness, 
and  eliminate  silica  in  the  usual  way,  but  without  weigh- 
ing it ;  add  water  to  the  filtrate  from  the  silica,  and  pre- 
cipitate sulphuric  acid  with  baric  chloride. 

/.  Hydratcd  aluminic  and  ferric  oxides.— To  deter- 
mine the  quantity  of  these  substances,  that,  according  to 
Knop,  play  so  im2)0itant  a  part  in  the  absorbent  action 


§    104.       MISCELLANEOUS    ESTIMATIONS.  187 

of  the  soil  for  valuable  elements  of  j^lant-food,  treat  100 
grms.  of  the  soil  with  200  c.c.  of  a  hot  solution  contain- 
ing in  one  litre  100  grms.  of  tartaric  acid,  10  grms.  of 
oxalic  acid,  and  ammonia  in  slight  excess ;  shake  the  mix- 
ture frequently  for  15  minutes,  filter,  and  determine 
aluminic  and  ferric  oxide  in  a  measured  quantity  of  the 
filtrate  (§  52).  The  oxalic  acid  in  the  solvent  serves  to 
prevent  lime  from  being  taken  up  by  the  tartaric  acid. 
In  order  to  prevent  alumina  also  from  being  dissolved, 
Mtiller  recommends  the  use  of  Seignette  salt  instead  of 
ammonic  tartrate. 

g.  Ferrous  oxide. — To  determine  this  at  least  approx- 
imately, pour  60  c.c.  of  hot  concentrated  hydrochloric 
acid  over  30  grms.  of  soil  in  a  flask ;  after  having  added 
a  few  crystals  of  sodic  carbonate,  if  the  soil  contains  but 
little  carbonate,  close  the  flasic  with  a  cork  through  which 
passes  a  short  tube  bent  at  a  right  angle,  put  the  flask  in 
an  inclined  j^osition  on  the  lamp-stand,  and  boil  the  mix- 
ture some  time.  Add  a  considerable  quantity  of  ammonic 
chloride  to  the  solution,  whereby  the  tendency  of  the 
ferrous  oxide  to  absorb  oxygen  is  very  much  lessened, 
dilute  with  a  large  quantity  of  hot  water,  almost  neutral- 
ize the  acid  with  ammonia,  and  precipitate  the  ferric 
oxide  in  the  solution  with  as  little  sodic  acetate  as  possi- 
ble (§  93,  -4,  1) ;  filter  the  hot  liquid  rapidly  through  a 
large,  coarse  filter,  and  wash  the  contents  of  the  filter 
several  times  with  hot  water;  heat  the" filtrate  and  wash- 
ings to  boiling,  add  some  hydrochloric  acid,  oxidize  the 
ferrous  oxide  by  the  addition  of  a  few  crystals  of  potassic 
chlorate,  remove  the  lamp,  and  precipitate  this  solution 
with  sodic  acetate,  filter,  wash,  and  weigh.  The  ignited 
residue  is  ferric  oxide,  from  which  the  corresponding 
amount  of  ferrous  oxide  can  be  calculated. 


188  §    105.       ANALYSIS    OF    SOILS    AXD    ROCKS. 

ABSORPTIVE  PROPERTIES  OF  THE  SOIL. 

105.  To  determine  the  coefficients  of  absorj)tion  of  the 
soil  for  the  more  important  elements  of  j^lant-food,  treat 
125  grms.  of  the  air-dried  soil  with  600  c.c.  of  a  ^1^^, 
atomic  solution,  that  is,  a  solution  containing  in  1  litre  ^  [.^ 
of  an  equivalent  expressed  in  grammes,  of  ammonic  chlo- 
rid<} ;  shake  the  mixture  frequently  during  a  cold  digestion 
of  24  hours,  decant  and  filter  as  large  a  portion  of  the 
liquid  as  possible,  and  determine  the  loss  of  the  salt  in  a 
measured  aliquot  part  of  the  filtrate.  In  some  cases  it  is 
desirable  also  to  make  a  complete  analysis  of  this  filtrate 
in  order  to  learn  what  elements  have  taken  the  place  of 
the  ammonium  in  the  solution. 

Make  similar  experiments  with  potassic  chloride,  mag- 
nesic  chloride,  calcic  chloride,  hydric  disodic  phosphate, 
sodic  chloride,  and  sodic  silicate. 

Or,  according  to  Knop's  method,  dissolve  together  po- 
tassic and  calcic  nitrate,  common  potassic  phosphate,  and 
magnesic  sulphate,  in  a  litre  of  water,  in  such  a  propor- 
tion that  the  solution  shall  contain  1.5  grms.  of  each  com- 
pound, estimated  as  anhydrous  salt.  Treat  125  grms.  of 
soil  with  500  c.c.  of  this  solution,  shake  the  mixture  fre- 
quently during  24  hours,  filter  oif  300  or  400  c.c,  and 
make  a  complete  analysis  of  the  solution,  according  to 
Scheme  T.,  a  and  i,  and  deteimine  chlorine  in  the  usual 
manner  in  another  portion  of  the  same  solution  (§  63) . 

STATEMENT  OF  THE  RESULTS  OF  THE  ANALYSIS. 

106.  The  following  Scheme  is  intended  to  assist  the 
analyst  in  putting  together  the  results  of  a  soil  analysis ; 
it  is  conformed  mainly  Avith  the  directions  given  by 
Wolff,  and  the  percentages,  though  hypothetical,  do  not 
differ  much  from  the  average  results  of  the  later  analyses 
of  soils  that  have  been  made ;  as  the  plan  is  given  merely 


/ 

§    106.      STATEMENT   OF   EESFLTS    OF   ANALYSIS.      189 

for  the  purpose  of  illustrating  the  manner  of  stating  the 
results  of  the  analysis,  many  of  the  determinations  which 
are  described  in  the  foregoing  pages  are  not  noticed  here. 
With  this  partial  guide,  no  difficulty  will  be  found  in 
stating  the  whole  result  of  the  w^ork  in  an  intelligible 
manner. 

MECHANICAL  ANALYSIS. 

100  parts  of  tlie  air-dried  soil  yielded 

I 

Water,  expelled  at  100^    9.34 

Residue  on  3  mm.  sieve,   6.05,  containing  volatile  matter 0.1 

"        "    1     "         "       7.69,  "  "  "      0.86 

Silt  in  Funnel  No.  2,      34.95,  "  "  "      3.73 

"      "        "  "    3,        17.7,  "  "  "      3.16 

"      "        "         "    4,        5.65,  "  "  "      0.82 

81.38 
Fineclayand  finest  sand,  18.62  "  "  "     2.48 

100.00    Total  loss  on  ignition  of  

soil  dried  at  100*        10.15 


190 


§    106.      ANALYSIS    OP   SOILS   AND   EOCKS, 


CHEMICAL  ANALYSIS. 
100  parts  of  the  soil  dried  at  100°  yielded 


5  =^5 
So    r 


Soluble  in  water 2.10 

Soluble  iu  alkali 1.25 


containing  nitrogen . 


Acids  of  humus ..,..3.25 

Humus  coal 1.75 

Other  organic  matter 1 .  25 

Ammonia 0.02 

Nitric  acid 0.009  

Total  nitrogen 0.0288 

Water  chemically  combined  or 

otherwise  retained  at  100° .1.221 

7.500 


0.01 

0.0165 

0.0023 


Carbonic  acid  (det.  in  another  portion) 0 .  14 ' 

Lime 0.17 

Magnesia 0.50 

Ferric  oxide 5.05 

Manganic  oxide traces 

Alumina 4.20 

Potassa ■ 0.06 

Soda 0.02 

Phosphoric  acid 0.15 

Sulphuric  acid 0. 04 

Silica 0.35 

Chlorine  (det.  in  aqueous  solution) 0.073 

iO?T53 

Deduct  oxygen  equivalent  to  the  chlorine .003 

10.75 


2> 


Co 

©hi " 
2  o 


(B^       fLime  0.31 

Magnesia 0.96 

And  so  on,  as  in  the  statement  of  the  analysis  of  the 
solution  in  cold  acid,  with  the  exception  of  Chlorine, 
and  the  addition  of  Silica,  (dissolved  out  of  the  resi- 
due insoluble  in  hot  acid,  by  boiling  sodic  carbon- 
ate)   

15.24 

>.  •*      r  Volatile  matter  expelled  on  ignition 1 .82 

■^Q        Lime 0.21 

Magnesia 0.31 

Ferric  oxide 1.03 

Alumina 1.76 

,    Potash 0.12 

^  ^  Soda 0.20 

Phosphoric  acid. 0 .  15 

Silica,  in  solution 0.14 

"     (dissolved  out  of  the  residue  insoluble 

InHaSO*  byhoilingNaaCOa 4.56 


as 

si 

'C.J, 
So" 

acccJ 


10.30 


s.::^ 


tcC  o 
s  o 


Lime 

tVAO.P. 

Ferric  oxide 

0.00 

Alumina 

Potnssa 

6.91 

3.20 

Soda 

2.11 

Silica 

44.00 

56.22 

§    107.       THE   PHYSICAL    QUALITIES    OF   THE   SOIL.     191 

100  parts  of  soil  dried  at  100°  C.  contain  of  clay  AI2O3  2Si02, 

2H2O,  estimated  from  tlie  alumina  and  silica  dissolved  by  acids 

(See  Table  III). 

a.  In  the  hydrochloric  acid  solutions 4.56 

h.    "     "   sulphuric  acid  solution 4.41 

100  parts  of  soil  dried  at  100°  contain  of 
a.  Fotassa  feldspar^   KaOjSSiOa,   AlaOsjoSiOa,  estimated  from  the 

potassa  in  the  solution  by  hydrofluoric  acid.     (See  Tabic  III.).18.94 
6.  Soda    feldspar^    Na20,3SiOo,  AlaOsjSSiOa,  estimated   from  the 

soda  in  the  solution  by  hydrofluoric  acid 17.85 

c.  Clay^  undecomposed  by  the  previous  treatment  with  sulphui-ic 

acid,  estimated  from  the  alumina  in  the  solution  by  hydro- 
fluoric acid  in  excess  of  what  is  required  for  the  feldsjDars 0.30 

d.  Pare  quartz  saiid^  estimated  from  the  silica  in  excess  over  what 

is  required  for  the  feldspars  and  clay 19.11 

(Estimated  also  from  the  determination  made  with  the  aid  of 
phosphoric  acid). 
100  parts  of  soil  dried  at  100°  C.  yielded  to  water  }{  saturated 
with  carbonic  acid 
Volatile  matter,  expelled  on  ignition  of  the  residue  left  by  evapo- 
ration of  the  extract 0.15  . 

Mineral  matters 0.19 

0.34 
THE  PHYSICAL  QUALITIES  OF  THE  SOIL. 


107.  Experiments  for  testing  the  physical  qualities  of 
the  soil,  and  for  comparing  different  soils  in  respect  to 
these  qualities,  should  be  made  with  soils  of  the  same  de- 
gree of  dryness  and  mechanical  division,  and  with  tolera- 
bly large  quantities,  and  the  observations  should  be  made 
under  circumstances  resembling  those  as  closely  as  j^ossi- 
ble,  by  which  the  soil  is  affected  in  the  field.  The  fol- 
lowing methods  have  been  carefully  tested  by  Wolff 
himself,  and  he  vouches  for  their  reliability. 

The  soil  must  be  comj^letely  air-dried,  pulverized  in  a 
porcelain  mortar  with  a  wooden  pestle,  or  rubbed  between 
the  hands  to  break  up  the  lumps  that  were  formed  in 
drying,  and  passed  througli  a  sieve  witli  meshes  3  mm. 
wide. 


192  §    107.       ANALYSIS    OF    SOILS    AND    EOCKS. 

a.  Relation  of  the  Soil  to  Vapor  of  Water. — 1, 
Power  of  retaining  liygroseopic  water  in  its  pores. — This 
is  measured  to  some  extent  by  the  determination  of  hy- 
groscopic moisture  (§  98).  The  j)roj)ortion  of  humus 
remaining  about  the  same,  the  power  of  the  soil  to  retain 
moisture  is  very  closely  related  to  the  amount  of  clay  it 
contains,  while  this  j)ower  is  greatly  increased  by  an 
increased  proportion  of  humus. 

2.  It  may  be  interesting  to  observe  the  relation  Of  tllis 
property  of  the  air-dried  soil  to  the  temperature.— 
For  this  purpose,  spread  a  layer  of  soil,  accurately  weigh- 
ed, about  3  mm.  thick  over  the  bottom  of  a  shallow  zinc 
tray,  and  note  the  changes  in  weight  from  day  to  day, 
when  it  is  exposed  to  direct  sunlight  while  protected 
from  currents  of  air,  or  when  exposed  to  a  temperature 
of  20°,  30%  and  40°  C. 

Also,  expose  the  soil  to  cm  atmosphere  that  is  saturated 
with  moisture^  by  putting  it  in  the  same  shallow  tray  to- 
gether with  a  shallow  vessel  of  w^ater,  under  a  bell-jar, 
and  weighing  it  three  or  four  times  every  24  hours.  An 
empty  tray  of  the  same  size  should  be  put  under  the  same 
bell-jar,  and  any  changes  in  the  weight  of  this  deducted 
from  the  differences  in  the  weight  of  the  other. 

Sandy  soils  and  loams  usually  become  nearly  saturated 
in  an  experiment  like  this,  in  the  first  24  hours,  and 
change  but  little  in  weight  thereafter. 

The  quantity  of  water  absorbed  varies  of  course  with 
the  temperature,  and  with  the  kind  of  soil ;  but  these 
variations  are  confined  within  narrower  limits  than  when 
the  soils  are  exposed  to  the  air  under  ordinary  circum- 
stances. The  amount  of  water  absorbed  from  this  satu- 
rated atmosphere  ranges  between  0.2  and  2.5°  1^,  of  the 
weiglit  of  the  completely  dry  soil. 

The  same  soil,  in  its  tray,  may  he  exposed  to  the  night 
air^  to  determine  the  amount  of  water  that  it  will  con- 
dense from  the  atmospliere  under  these  circumstances ; 


§    107.       THE   PHYSICAL    QUALITIES    OF   THE    SOIL.      193 

careful  observations  should  be  made,  at  the  same  time,  of 
the  temperature,  the  clearness  of  the  sky,  and  the 
amount  of  the  dew-fall,  and  the  experiment  should  be 
performed  over  a  grass  plot  as  well  as  over  a  freshly 
stirred  soil. 

With  an  average  dew-fall,  the  amount  of  water  taken 
up  by  a  soil  above  what  it  contains  in  the  air-dried  state 
varies,  with  different  kinds  of  soil,  between  0.4  and  1.8°  [^ 
of  the  weight  of  the  completely  dried  soil. 

Finally,  to  test  the  effect  of  the  depth  of  the  soil  on 
its  power  of  absorbing  moisture  under  these  different  cir- 
cumstances, several  trays  or  boxes,  of  say  ^l^,  V\^^  3,  and 
6  cm.  deep,  and  5  cm.  square,  may  be  filled  with  air-dried 
soil,  in  all  cases  equally  dry  and  finely  pulverized,  and 
the  whole  exposed  to  the  ordinary  atmospheric  influ- 
ences, or  to  a  saturated  atmosphere,  or  to  the  night  air, 
in  the  manner  directed  above. 

By  such  experiments  we  may  determine  how  much 
moisture  is  absorbed  by  layers  of  soil  of  different  thick- 
nesses within  a  certain  length  of  time,  how  far  the  moist- 
ure penetrates  into  different  soils  in  equal  times,  and  how 
long  a  time  is  required  to  saturate  layers  of  different 
thicknesses  in  a  saturated  atmosphere. 

b.  The  Relation  of  the  Soil  to  Liquid  Water  ix  its 
Pores.— 1.  To  determine  the  power  of  the  soil  to  retain 
liquid  water  in  its  pores,  construct  a  zinc  box,  17  cm.  deep, 
and  3  cm.  square,  and  pierce  its  bottom  with  numerous 
small  holes ;  lay  over  this  bottom  a  piece  of  moistened 
fine  Imen,  and  Aveigh  the  box  ;  then  put  in  a  small  quan- 
tity of  the  properly  dried  and  pulverized  soil,  taj)  the 
box  gently  on  the  table  a  few  times,  and  proceed  in  the 
same  manner  until  the  box  is  full,  and  weigh  again. 
Then  immerse  the  bottom  of  the  box  in  water  to  the 
depth  of  3-4  mm. ;  the  water  appears  at  the  surface  of 
the  soil  sooner  or  later,  according  to  the  nature  of  the 
latter  ;  let  the  apparatus  vemain  in  the  water  until  |t  suf- 
9 


194  §    107.      ANALYSIS    or    SOILS    AND    EOCKS. 

fers  no  further  change  m  weight,  and  then  calculate  the 
amount  taken  uj)  by  100  parts  of  the  air-dried  soil. 

As  this  box,  with  its  wet  soil,  is  used  subsequently  for 
experiments  in  the  course  of  which  tlie  soil  is  dried 
again,  this  trial  may  then  be  repeated  ;  some  soils  shrink, 
while  drying,  to  a  greater  extent  than  others,  and  it  will 
be  found  that,  in  this  second  trial,  the  power  of  holding 
water  will  not  be  the  same  as  at  first.  The  difference, 
however,  is  but  slight. 

The  power  of  a  soil  to  hold  liquid  water  increases  with  . 
the  proportion  of  humus,  but  diminishes  as  the  quantity 
of  clay  increases.  A  strong  clay  soil  may  retain  27.3"  |^, 
a  moderately  heavy  soil  30-31°  |^,  a  sandy  loam  33-36°!^, 
a  black  loam,  rich  in  humus,  41°  1^.  When  some  soils, 
that  had  been  tested  as  above,  were  tested  also  in  their 
natural  position  in  the  field,  after  a  rain  of  14  days,  when 
they  might  be  supposed  to  be  saturated,  they  were  found 
to  contain  10"  j^  less  than  was  indicated  by  the  results  of 
experiments  in  the  laboratory ;  hence,  the  determinations 
made  with  small  quantities  in  zinc  boxes,  appear  to  have 
value  only  in  so  far  as  they  enable  us  to  compare  the 
water-holding  powers  of  different  soils. 

2«  To  determine  the  readiness  with  which  water  evap- 
orates from  the  soil,  the  wet  or  damp  soil  may  be  ex- 
posed, in  a  shallow  tray,  to  the  air,  at  the  common  sum- 
mer temperature,  or  at  that  of  the  laboratory ;  but  so 
long  as  a  considerable  proportion  of  w^ater  is  present,  the 
rate  of  evaporation  remains  about  the  same  for  all  soils, 
provided  only  that  the  same  amount  of  surface  is  exposed; 
it  is  also  very  slow,  months  being  required  to  bring  100- 
150  grms.  of  soil,  in  a  layer  no  more  than  4-6  cm.  thick, 
to  the  condition  of  air-dried  soil. 

When,  however,  natural  circumstances  are  more  closely 
imitated,  and  a  sufficiently  thick  layer  of  soil  is  experi- 
mented with  and  exposed  to  the  usual  alternation  of  direct 
sunlight  and  shade,  the  characteristic  differences  of  soils 


§    107.       THE    PHYSICAL    QUALITIES    OF   THE   SOIL.     195 

appear.  For  a  standard  of  comparison  it  would  be  well 
to  carry  on,  simultaneously,  one  or  two  similar  trials  with 
soils  of  a  marked  character,  such  as  a  very  strong  clay 
soil  and  a  very  sandy  one,  that  have  been  tested  before 
in  this  respect. 

To  make  the  determination,  use  the  zinc  box  filled  ^v^th 
wet  soil,  that  was  obtained  in  testing  the  water-holding 
power ;  put  each  box  with  its  contents  in  a  second  box 
of  thick  pasteboard,  into  which  it  just  fits,  and  then  put 
all  these  pasteboard  boxes  close  together  in  a  third 
wooden  box,  just  as  deep  as  the  zinc  boxes;  provide  the 
wooden  box  with  a  cover,  in  which  holes  are  so  cut  that, 
when  the  cover  is  on  the  box,  only  the  surface  of  earth  in 
each  zinc  box  is  exposed. 

Put  the  whole  where  the  sun's  rays  can  fall  on  the  soil, 
and  weigh  each  zinc  box  with  its  contents  every  two  or 
three  days,  and  during  a  length  of  time  varying  from,  two 
to  four  weeks,  according  to  the  weather ;  frequent  ob- 
servations of  the  temperature  and  the  state  of  the  sky 
should  be  made,  while  the  evaporation  is  going  on. 

It  will  be  observed  that,  in  the  beginning,  the  rate  of 
evaporation  is  about  the  same  for  all  the  varieties  of  soil 
under  examination,  even  when  exposed  to  the  rays  of  a 
hot  sun  ;  after  a  time  the  sandy  soils  begin  to  lose  weight 
more  rapidly  than  those  in  which  clay  or  humus  pre- 
dominates ;  the  difierence  increases  up  to  a  certain  point, 
and  then  begins  to  diminish,  until,  after  a  time,  the  rate 
of  evaporation  is  nearly  the  same  again  for  all ;  this  con- 
tinues for  a  time,  and  then  the  clay  and  humus  soils  begin 
to  lose  water  more  rapidly  than  the  light  loam,  because 
the  latter  is,  by  this  time,  nearly  air-dry. 

It  is  of  course  more  important  to  watch  carefully  the 
rate  of  evaporation,  from  the  time  when  it  begins  to  differ 
in  the  different  soils,  to  the  time  when  it  again  becomes 
about  the  same  for  all. 


196  §    107.       ANALYSIS    OF    SOILS    AND    KOCKS. 

3.  To  determine  the  ease  with  which  water  perco- 
lates through  the  soil,  construct  a  ziac  box  about  25  cm. 
high  aud  3  cm.  square,  with  a  funnel-like  bottom;  put 
some  cotton  in  the  bottom,  so  as  to  close  up  the  throat 
of  the  funnel,  and  fill  the  narrow  tube,  and  extend  out  a 
little  at  the  mouth  of  the  latter.  Fill  the  funnel  above 
the  cotton  with  coarse  quartz  sand,  moisten  the  cotton 
and  sand  with  water,  and  weigh  the  apparatus ;  then 
carefully  fill  the  box  with  the  properly  prepared  earth, 
putting  in  small  quantities  at  a  time,  and  tapping  the  box 
on  the  table  after  each  portion  is  added  ;  when  the  box  is 
filled  to  within  9  cm.  of  the  top,  w^eigh  the  whole  again ; 
then,  just  saturate  the  soil  by  carefully  pouring  on  water 
in  small  quantities  at  a  time,  until  it  appears  at  the 
bottom ;  when  it  has  ceased  to  drop  through,  weigh  the 
box  and  its  contents  again,  and  the  result  may  be  used 
to  confirm  that  obtained  before  for  the  water-holding 
power  of  the  soil. 

Now  carefully  fill  the  box  with  water  to  within  1  cm. 
of  the  top  without  disturbing  the  surface  of  the  soil, 
cover  with  a  glass  plate,  and  observe  how  long  a  time  is 
required  for  50  c.c.  of  water  to  pass  tlirough.  If  the 
operation  is  repeated,  by  filling  the  box  with  water  again, 
after  the  first  quantity  has  passed  through,  it  will  be 
found  that  a  somewhat  longer  time  is  I'equired ;  three 
such  tests  may  be  made,  and  the  mean  of  the  three  re- 
sults taken. 

4.  To  determine  the  rapidity  with  which  water  will 
move  upwards  in  the  soil,  fill  a  glass  tube  about  80  cm. 
high  and  1.5-2  cm.  in  diameter,  graduated  in  cubic  cen- 
timetres, and  closed  at  its  lower  end  with  a  piece  of  fine 
linen  that  is  tied  over  the  end,  with  the  air-dried  soil,  tap- 
ping the  tube  gently  on  the  table  while  filling  it ;  then 
immerse  the  lower  end  of  the  tube  in  water  3-4  mm. 
deep,  and  observe  how  long  a  time  is  required  for  the 
Avater  to  rise  to  a  height  of  70  or   80  cm.,  or  how  high 


§    107.       THE    PHYSICAL    QUALITIES    OP   THE    SOIL.     197 

the  water  will  rise  in  24  or  48  hours ;  it  will  be  found 
to  rise  more  slowly  in  humus  and  clay  soils  than  in  light, 
sandy  ones. 

5.  The  rapidity  with  which  water  will  make  its  way 
downwards  in  the  soil  may  be  determined  in  the  same 
tube,  partly  filled  with  a  fresh  quantity  of  earth  ;  fill  the 
tube  above  the  soil  with  water  to  the  depth  of  4-8  cm., 
and  note  the  time  required  until  it  has  reached  a  given 
depth,  or  how  soon  the  water  disappears  from  the  surfjice 
of  the  soil,  r.nd  also  how  far  a  given  quantity,  that  is  in- 
suflScient  to  make  its  way  through  and  moisten  the  soil 
quite  to  the  lower  end,  will  penetrate  downwards. 

It  will  be  found  that  the  same  quantity  of  water  will 
go  furthest  in  a  fine  loam  or  a  sandy  soil. 

c.  The  Rel4.tiox  of  the  Soil  to  Heat. — 1,  To 
determine  the  power  of  the  soil  to  absorh  heat,  fill  a 
cubical  zinc  box,  about  6  cm.  square,  with  soil,  expose  it 
several  hours  to  the  direct  rays  of  the  sun  on  a  hot  day, 
carefully  observe  the  temperature  in  the  sun  during  the 
experiment,  and  the  elevation  of  temperature  in  the  up- 
permost centimetre  of  the  soil.  The  zinc  box  should  be 
inclosed  in  a  box  of  thick  pasteboard,  and  tins  in  a  wooden 
box,  to  prevent  access  of  heat  at  the  sides. 

It  may  also  be  interesting  to  observe  the  heating  power 
of  the  sun's  rays  on  the  soil,  while  it  is  in  a  more  or  less 
moist  condition,  say  with  5, 10,  or  20°  1^  of  water,  more 
than  that  naturally  present  in  the  soil.  Such  determina- 
tions may  be  made  by  exposing  about  50  grms.  of  the 
moistened  soil  for  several  hours  in  a  glass  flask  to  the 
direct  rays  of  the  sun,  and  noting  the  changes  of  tem- 
perature. 

2.  The  power  of  the  soil  to  conduct  heat  may  be  de- 
termined by  putting  the  same  box,  as  used  in  the  previ- 
ous experiment,  into  hot  water,  and  observing  how  long 
a  time  elapses  before  the  temperature  of  the  earth  in  the 


198  §    107.       ANALYSIS    OF    SOILS    AND    EOCKS. 

centre  of  the  box  has  reached  a  given  point,  say  70^  or 
80°  C. 

3.  The  power  of  the  soil  to  retain  heat  may  be  de- 
termined by  exposing  the  box  of  heated  soil,  obtained  in 
either  of  the  preceding  experiments,  to  the  common  tem- 
perature of  the  air  in  the  shade,  and  observing  how  long 
a  lime  is  required  for  the  soil  in  the  middle  of  the  box  to 
cool  to  the  temperature  of  tlie  air,  or  to  a  given  point,  as 
20°  or  25°  C. 

The  behavior  of  the  soil  with  respect  to  the  heat  of  the 
sun  and  of  the  atmosphere  is  of  great  agricultural  im- 
portance, and  should  be  more  carefully  examined  than 
has  hitherto  been  the  case,  by  the  careful  performance  of 
experiments  like  those  described  above,  and  by  series  of 
observations  on  the  temperature  of  the  soil  in  tlie  field  at 
various  depths,  ranging  from  3  cm.  down  to  one  metre  or 
more. 

d.  The  Specific  Gravity  of  the  Soil. — 1.  This  may 
be  determined  in  the  usual  manner  for  a  powder  (§  35,  5). 

A  soil  rich  in  humus  is  specifically  the  lightest,  and 
coarse  sandy  soils  are  the  heaviest. 

2.  The  absolute  weight  of  the  soil  is  determined  by 
filling  a  glass  vessel,  or  a  cubical  zinc  box,  whose  weight 
and  capacity  are  known,  with  it,  tapping  the  vessel  occa- 
sionally on  the  table  while  filling  it,  and  weighing  it.  The 
weight  of  a  cubic  metre  or  a  cubic  foot  can  then  be  cal- 
ctdated  from  the  result;  the  apparent  specific  gravity 
can  be  estimated  by  the  ratio  between  the  weight  of  this 
volume  of  soil  and  that  of  an  equal  volume  of  water. 

3.  The  apparent  specific  gravity  of  the  soil  dried  at 
100°  C.  may  be  estimated  by  subtracting  the  volume  of 

.  the  water  contained  in  the  quantity  of  air-dried  soil  that 
was  weighed  in  this  experiment  from  the  volume  of  the 
soil,  and  then  a  volume  of  water  equal  to  the  remainder  is 
taken  for  the  divisor,  and  the  weight  of  the  soil  dried  at 
100°  for  the  dividend. 


§    107.       THE    PHYSICAL    QUALITIES    OF   THE    SOIL.      199 

4.  The  porosity  of  the  soil,  or  the  ratio  between  the 
volume  of  the  solid  particles  and  that  of  the  spaces  in  it 
filled  with  air  or  moisture,  is  estimated  by  dividing  the 
apparent  specific  gravity  of  the  soil,  dried  at  100°,  by  the 
real  specific  gravity.  Or  if,  for  example,  2.5445  =  the 
real  specific  gravity  of  a  certain  soil,  and  1.099  its  ap- 
parent  specific  gravity,  then  from  the  proportion, 

2.5445  :  1.099  =  100  :  43.2, 
we  get  the  volume  of  the  solid  particles  in  100  parts  of 
the  soil,  and  100-43.2  =  56.8  =  the  volume  of  the  pores. 

The  porosity  of  the  soil,  just  as  it  lies  in  the  field,  may 
be  estimated  in  a  similar  manner,  by  taking  as  the  volume 
of  the  soil  the  space  that  was  occupied  by  the  quantity 
taken  out  to  be  weighed. 

To  determine  the  volume  occupied  by  the  soil  when 
completely  saturated  with  water,  determine  the  volume 
of  40-50  grms.  of  the  air-driecl,  pulverized  soil  in  a 
graduated  tube,  that  was  filled  with  the  earth  in  small 
portions  at  a  time,  with  occasional  tapping  on  the  table, 
shake  the  soil  up  well  with  water  containing  0.5°  1^  of  am- 
monic  chloride ;  then  let  the  whole  stand  quietly,  while 
the  solid  particles  collect  together  in  the  lower  part  of 
the  tube,  and  observe  the  volume  occupied  by  this  wet 
soil.  By  dividing  the  second  volume  by  the  first,  the  re- 
sult is  put  in  a  convenient  form  for  comparison. 

e.  Consistency,  Tenacity,  and  Adhesive  Power  of 
THE  Soil. — The  consistency  of  the  soil  when  dry,  its 
tenacity,  and  the  force  with  which  it  adheres  to  wood  and 
iron,  are  very  important  qualities ;  but  it  is  hardly  pos- 
sible, by  any  of  the  methods  in  use  for  estimating  them, 
to  get  even  approximately  accurate  results  with  small 
quantities  of  soil.  The  following  methods  were  devised 
and  used  by  Schiibler  thirty  years  ago. 

1.  To  determine  the  consistency  of  the  soil,  or  the 
force  with  which  its  particles  cohere  together  when  dry, 


200  §    108.       ANALYSIS    OF    SOILS   AND    KOCKS. 

knead  a  small  portion  of  it  into  a  thick  dough  with  wateiv 
and,  with  a  spatula,  make  several  prisms  5  cm.  long,  and 
1  cm.  square  on  the  end ;  let  them  dry  in  the  air,  and 
then  observe  what  weight  must  be  laid  on  the  back  of  a 
knife  in  order  to  force  it  through  each  one.  The  same 
prisms  may  be  used  to  determine  how  much  the  soil 
shrinks  on  drying,  by  noting  the  difference  between  their 
lengths  when  wet  as  at  first,  and  after  they  are  dry. 

2.  To  determine  the  force  with  which  the  soil  adheres 
to  wood  or  iron,  fill  a  cubical  zinc  box  about  6  cm.  square 
and  deep,  whose  bottom  is  j)ierced  with  small  holes,  and 
covered  with  a  piece  of  linen,  with  the  soil,  shaking  it 
down  frequently  while  filling  ;  then  immerse  the  bottom 
of  the  box  in  water,  and,  w^hen  no  further  increase  of 
w^eight  is  observed,  lay  a  smooth  piece  of  beech  wood,  3 
cm.  square,  on  the  wet  surface  of  the  soil,  press  it  down 
for  the  space  of  ten  minutes,  by  a  w^eight  of  100  grms., 
attach  the  disk  to  one  arm  of  a  balance,  and  observe  what 
weight  must  be  put  in  the  pan  connected  with  the  other 
arm,  in  order  to  detach  the  disk  from  the  soil.  Try  a 
similar  experiment  witli  a  disk'  of  iron. 

EXPERIMENTS  WITH  PLANTS  IN  CONNECTION  WITH  ANALY- 
SIS OF  SOILS. 

108.  The  further  development  of  soil  analysis  on  one 
hand,  and  its  simplification  on  the  other  by  eliminating 
useless  or  unnecessary  determinations,  can  be  accom- 
plished only  by  combining  suitable  experiments  with 
modes  of  culture  and  manuring,  and  growling  plants,  with 
accurate  analyses  of  the  soils  used. 

In  the  field  but  little  can  be  done  in  this  way,  since  so 
much  care  and  labor  are  required,  in  order  to  obtain  a 
tolerably  fair  representative  sample  of  the  soil,  even  of  a 
small  plot. 

iSTot  seldom,  however,  a  more  luxuriant  vegetation  is 


§    108.       EXPERIMENTS  WITH    PLANTS  AND  SOILS.      201 

observed  in  one  part  of  a  field  than  in  another,  although 
the  nature  of  the  soil  and  the  mode  of  treatment  are  ap- 
parently the  same  throughout ;  in  such  a  case,  much  may 
possibly  be  learned,  by  a  careful  comparison  of  the  amounts 
of  the  crops  taken  from  the  two  parts  of  the  field,  and  a 
search  for  the  cause  of  the  difference  by  a  careful  exami- 
nation of  the  soil.  Of  course  the  nature  of  the  subsoil 
should  be  ascertained,  down  to  the  depth  of  a  metre  or 
so,  in  order  to  be  sure  that  the  cause  of  the  phenomenon 
does  not  Ife  there,  perhaps  in  some  accumulation  of  water, 
or  a  great  difference  in  the  mechanical  or  physical  charac- 
ters of  this  subsoil. 

Actual  experiments  with  manures  and  growing  j^lants, 
to  be  combined  with  soil  analysis,  are  best  made  in  boxes 
of  soil  that  has  been  carefully  sifted  and  mixed  ;  a  perfect 
sample  of  such  a  soil  can  be  obtained  without  difficulty. 

The  wooden  boxes  to  contain  the  soil  for  these  experi- 
ments may  be  made  abo^.t  one  metre  deep,  and  half  a 
metre  square,  and  with  several  holes  through  the  bottom. 
They  should  be  set  in  the  ground  in  a  grass  plot,  so  that 
they  will  project  but  3-5  cm.  above  the  surface.  The 
soil  with  which  they  are  to  be  filled  should  be  pulverized 
when  in  a  very  moderately  moist  condition,  by  rubbing 
it  between  the  hands,  or  with  a  wooden  pestle  in  a  porce- 
lain mortar,  and  passed  through  a  sieve  with  meshes  6-8 
mm.  wide ;  an  ample  quantity  of  it  should  be  provided, 
so  that  there  may  be  enough  for  the  analysis  and  for  all 
possible  contingencies,  besides  what  is  required  to  fill  up 
the  box. 

To  fill  the  box,  put  a  layer  of  gravel  5-8  cm.  thick 
over  the  bottom,  and  then  add  the  soil,  pressing  it  down 
gently,  as  it  is  put  in  in  small  portions  at  a  time ;  then 
pour  a  quantity  of  rain-water  over  the  soil,  equal  to 
about  half  that  which  it  can  retain  in  its  pores  ;  stir  up 
the  surface  and  fill  with  more  soil,  up  to  the  edge  of  the 
box,  and,  if  possible,  before  sowing  the  seed,  or  putting 
9* 


202  §    108.       ANALYSIS    OF    SOILS    Ai!«-D    llOCKS. 

in  j)laiits,  let  the  whole  stand  several  weeks,  so  that  it 
may  settle  together  and  assume  a  perfectly  natural  con- 
dition. 

If  the  boxes,  when  put  in  place,  are  not  surrounded  by 
grassy  turf,  the  same  plants  as  those  cultivated  in  them 
should  be  grown  around  them,  so  that  there  can  be  no 
disturbing  influences  from  fresh  soil. 

When  the  seed  is  to  be  sown,  put  in  more  fresh  soil  if 
it  is  necessary,  in  order  to  bring  the  surface  up  even  w*ith 
the  edge  of  the  box.  In  sowing  the  seed,  and  in  the  sub- 
sequent cultivation  of  the  plant,  the  usual  rules  of  good 
culture  should  be  observed  as  far  as  possible,  as  respects 
depth  of  sowing,  distance  apart  of  the  plants,  and  other 
matters.  For  experiments  with  the  cereals,  which  are  of 
the  greatest  importance,  oats  and  rye  are  best,  since  these 
plants  are  less  liable  to  disease,  or  to  be  destroyed  by 
birds. 

The  foUoAving  are  a  few  of  the  great  number  of  inter- 
esting experiments  that  can  be  performed  in  these  boxes 
of  prepared  soil. 

Three  or  four  soils  may  be  prepared,  differing  great- 
ly in  the  amount  of  sand  and  clay  they  contain,  but 
closely  resembling  each  other  as  regards  the  lime  and  hu- 
mus. Kot  only  the  quantity  of  the  crop  should  be  ob- 
served, but  also  its  quality^  such  as,  in  the  cereals,  for 
example,  the  proportion  of  grain,  straw,  and  chaff,  of 
light  and  heavy  grains,  the  specific  gravity  of  the  grain, 
the  number  of  the  stalks  and  the  degree  of  maturity  at- 
tained by  them,  the  weight  of  the  stubble  and  main  roots, 
and  the  proximate  chemical  composition  of  the  different 
parts  of  the  j)lant. 

With  such  observations  as  these,  combined  with  an  ac- 
curate knowledge  of  the  composition  of  the  soil,  we 
should  soon  learn  whether  any  direct  relation  exists  be- 
tween the  proportion  of  plant-food  in  the  soil,  that  is 
soluble  in  water  or  cold  or   hot  hydrochloric  acid,  and 


§   108.       EXPERIMENTS  WITH    PLANTS  AND  SOILS.       203 

the  quantity  or  quality  of  the  crop,  or  whether,  as  is 
probably  the  case,  the  proportion  between  the  clay  and 
these  soluble  substances,  or,  in  other  words,  the  physical 
character  of  the  soil,  exerts  a  controlling  influence  on  its 
fertility. 

It  would  be  well  to  jierform  three  experiments  of  the 
same  character  with  each  kind  of  soil,  partly  for  the  pur- 
pose of  securing  greater  certainty  in  the  results,  and 
partly  that  the  same  soil  may  be  used  afterwards  for  other 
experiments. 

To  test  the  question  whether  the  substances  in  the  soil 
tliat  are  soluble  in  pure  or  carbonated  water  exert  any 
essential  influence  on  its  immediate  productiveness,  a  trial 
may  be  made  with  a  soil  in  its  natural  condition,  and  with 
the  same  or  a  similar  soil,  after  it  has  been  exhausted  with 
water  in  the  manner  described  for  the  preparation  of  an 
aqueous  solution  for  chemical  analysis  (§  100).  As,  how- 
ever, it  would  be  very  inconvenient  to  exhaust  such  a 
quantity  of  soil  in  this  way,  as  would  be  required  to  fill 
one  of  the  boxes,  this  experiment  may  be  performed  with 
but  7-10  kilos,  of  soil,  in  smaller  boxes,  or  in  glass 
vessels.  The  plants  should  be  watered  with  distilled 
water  during  the  progress  of  the  experiment. 

Valuable  results  may  be  obtained  from  experiments  in 
which  equal  quantities  of  assimilable  plant-food  are  added 
to  different  varieties  of  soil. 

The  action  of  a  full  and  complete  provision  of  the  ele- 
ments of  plant-food  on  one  kind  of  plant  grown  in  the 
different  soils,  should  first  be  examined.  For  such  a 
complete  manuring,  we  need  only  to  mix  together  acid 
potassic  phosphate,  calcic  nitrate,  j)otassic  nitrate,  and 
magnesic  sulphiite,  so  that  the  relative  proportions  of 
the  bases  in  the  mixture  will  be  the  same  as  in  the  ash 
of  the  plant  to  be  cultivated. 

For  this  purpose,  the  boxes  and  soils  employed  in  pre- 
vious   years  for    trials    with    soils    containing    different 


204  §    108.       ANALYSIS    OP    SOILS    AND    ROCKS. 

amounts  of  sand  and  clay  may  be  used  ;  one  box  of  each 
kind  of  soil  should  have  nothing  added  to  it,  so  as  to  have 
a  standard  with  which  to  compare  the  effect  of  the  ma- 
nuring in  other  soils  of  the  same  nature.  From  the  aver- 
age crops  of  the  preceding  year  in  all  the  boxes,  an  esti- 
mate may  be  made  of  the  quantity  of  plant-food  to  be 
added. 

The  soil  to  be  manured  is  taken  out  of  the  box  to  the 
depth  of  30  cm. ;  ^  |^  of  this  is  intimately  mixed  with  the 
aqueous  solution  of  the  salts  to  be  added,  and  this  in  its 
turn  is  intimately  mixed  with  the  remaining  ^|j  of  the 
soil,  by  rubbing  the  two  together  carefully  between  the 
hands  ;  the  whole  is  then  put  back  into  the  box. 

Instead  of  the  solution  of  the  above  salts,  the  actual 
practice  with  manures  may  be  more  closely  imitated  by 
making  an  aqueous  extract  of  a  superphosphate,  deter- 
mining the  amount  of  phosphoric  acid  in  the  solution,  and 
dissolving  therein  the  2:)roper  amounts  of  crude  potassic 
chloride,  sodic  nitrate,  and  magnesic  sulphate. 

In  a  similar  manner,  the  effect  of  an  increased  propor- 
tion of  humus  in  the  soil  may  be  studied,  by  letting  some 
sawdust  of  a  soft  wood,  free  from  resin,  partly  decay, 
making  an  aqueous  extract  of  this,  or  of  some  other  suit- 
able substance  rich  in  humus,  and  mixing  this  solution 
with  the  soil  in  the  way  already  described. 

Other  matters  that  might  be  profitably  studied  in  this 
connection  are,  the  effect  of  lime^  of  the  concentrated 
commercial  manures,  and  the  relation  between  the  co- 
efficients of  absorption  of  the  soil  for  the  various  ele- 
ments of  plant-food,  and  its  fertility. 


§    109.      MARL.  205 

II. 

ROCKS  AND  THE  PRODUCTS  OF  THEIR  WEATHERING. 

109.  The  object  of  analyzing  a  rock,  for  agricultural 
purposes,  may  be  to  estimate  the  total  amount  of  its  con- 
stituents, or  to  determine  its  solubility  and  the  readiness 
with  which  it  would  be  disintegrated  and  converted  hito 
soil  on  exposure  to  the  air.  The  method  of  the  analysis 
would  be  much  the  same  as  that  already  described  for  the 
analysis  of  soils.  A  qualitative  examination  should  pre- 
cede the  quantitative  one,  in  order  to  learn  the  best  way 
of  bringing  the  mineral  into  solution,  as  well  as  what 
substances  arc  to  be  separated  and  determined. 

The  examination  of  the  products  of  the  weathering  of 
a  rock  should  be  conducted  in  the  same  manner  as  a  i-egu- 
lar  soil  analysis,  by  treating  it  with  the  same  solvents  in 
the  same  succession. 

The  three  more  important  substances  that  come  under 
this  head  are  marl,  limestone,  and  clay,  and  some  special 
directions  for  the  analysis  of  each  may  be  useful. 

MARL. 

As  this  substance  is  used  by  the  farmer  in  its  natural 
condition,  it  should  be  taken  in  a  similar  condition,  for 
analysis,  viz.,  air-dried  and  unignited.  If  taken  fresh 
from  the  pit,  it  should  be  allowed  to  lie  for  a  long  time 
exposed  to  the  air  on  filter-paper,  until  thoroughly  dry. 

The  most  useful  of  the  determinations  mentioned  below 
are  those  of  phosphoric  acid  and  the  alkalies,  and  the  me- 
clianical  analysis. 

The  mechanical  mialysls.  For  this,  which  is  of  much 
importance,  since  the  value  of  a  marl  usually  depends 
largely  on  the  fineness  of  the  division  of  its  particles, 
treat  30-50  grms.,  according  to  the  amount  of  calcic  car- 


206  §    109.       ANALYSIS    OF    SOILS    AND    EOCKS. 

bonate  contained  in  it,  with  dilute  hydrocliloric  acid  in  a 
flask,  as  long  as  there  is  any  effervescence,  wash  the  resi- 
due, boil  it  half  an  hour  with  water,  and  then  subject  it 
to  the  silt  analysis  (§  97). 

Or,  if  it  is  desired  to  determine  the  fineness  of  division 
of  the  calcic  carbonate  in  the  marl,  the  whole  may  be 
subjected  to  the  silt  analysis  without  previous  treatment 
with  acid,  and  then  the  carbonate  can  be  determined  in 
the  contents  of  each  funnel. 

If  the  marl  does  not  fall  to  a  fine  powder  in  water,  it 
must  first  be  sifted,  as  directed  for  the  preparation  of  the 
soil  for  the  silt  analysis. 

For  practical  purposes,  the  following  rough  method  of 
estimating  the  fineness  of  the  marl  will  often  answer. 

After  treating  10  grms.  of  the  marl  with  hydrochloric 
acid  as  long  as  there  is  any  effervescence,  i:)our  a  consid- 
erable quantity  of  water  over  the  residue,  with  constant 
stirring,  let  the  sand  and  heavier  particles  settle,  and  de- 
cant the  turbid  liquid  holding  clay  in  suspension  ;  repeat 
the  same  operation  with  the  residue  several  times,  until 
the  water  is  clear  after  the  sand  settles  to  the  bottom, 
collect  the  latter  on  the  filter,  ignite,  and  weigh  as  coarse 
sand. 

The  chemical  analysis. 

a.  Water. — Dry  about  10  grms.  of  the  substance  at 
100°  C,  and  determine  the  loss  of  weight. 

h.  Carbonic  acid. — Determine  this  in  2-4  grms.,  as  di- 
rected in  §  60. 

For  practical  purposes,  the  following  method  will  usu- 
ally yield  sufiiciently  accurate  results. 

Weigh  out  2-3  grms.  of  the  marl  in  a  flask  of  about 
100  c.c.  capacity,  moisten  it  with  a  little  water,  carefully 
lower  into  the  flask  a  small  test-tube,  ^|j  filled  with  hydro- 
chloric acid,  in  such  a  way  that  no  acid  can  escape  into 
the  flask,  and  weigh  the  Avhole ;  then  cause  the  acid  to 
flow  out  of  the  test-tube  into  the  flask  by  inclining  the 


§    109.      MAEL.  207 

latter,  and,  while  the  effervescence  continues,  let  the  flask 
lie  in  an  inclined  position,  with  the  end  of  the  test-tube 
partly  stopping  up  its  mouth.  When  the  effervescence 
lias  ceased,  blow  air  into  the  flask  to  remove  the  carbonic 
acid  gas,  weigh  the  whole  again,  and  count  the  loss  as  car- 
bonic acid  ;  the  results  w^ill  be  within  0.25°  1^  of  the  truth. 

c.  Lime  and  Magnesia. — Digest  2-3  grms.  of  the  well- 
pulverized  marl  with  dilute  hydrochloric  acid,  and  exam- 
ine the  solution  more  particularly  for  lime  and  magnesia, 
as  under  b,  Scheme  lY.,  §  94. 

d.  Phosphoric  acid  and  the  alkalies. — Allow  300  c.c. 
of  concentrated  hydrochloric  acid  (Sp.  Gr.  =  1.15)  to  act 
on  100  grms.  of  the  well-pulverized  marl  in  a  large  flask, 
for  48  hours  at  common  temperatures,  with  frequent  agi- 
tation; (or,  take  120  grms.  of  soil  and  360  c.c.  of  acid,  if 
ferric  oxide  and  alumina  are  to  be  determined,  and  esti- 
mate them  in  '  |g  of  the  solution  obtained  ;  this  detennina- 
tion,  however,  will  not  generally  be  important). 

Decant  the  solution  from  the  insoluble  residue,  dilute 
with  some  water,  filter,  put  the  insoluble  residue  on  the 
filter,  and  wash  it  first  with  cold  and  afterwards  with  hot 
water.  Evaporate  the  filtrate  to  dryness,  and  remove 
silicic  acid. 

Examine  the  filtrate  from  the  silica  as  under  b,  in 
Scheme  I,  §  94. 

If  the  marl  contains  a  large  proportion  of  clay,  some 
of  the  phosphoric  acid  may  remain  undissolved  by  the 
cold  concentrated  acid.  In  this  case,  boil  about  50  grms. 
of  the  marl  one  hour  with  150  c.c.  of  concentrated  acid, 
filter,  eliminate  silica,  and  proceed  to  determine  phosphoric 
acid,  as  above. 

The  insoluble  residue,  left  after  treatment  of  the  marl 
with  cold  acid,  and  composed  of  clay  and  sand,  is  dried 
in  the  air-bath,  left  for  a  considerable  time  expoced  to  the 
air,  and  weighed.  If  from  this  we  subtract  the  weight 
of  coarse  sand,  obtained  by  the  rough  method  in  the 


208  §    109.       ANALYSIS    OF    SOILS    AND    HOCKS. 

mechanical  analysis,  we  h^ve  left  the  amount  of  fine  sand 
and  clay. 

Treat  this  residue  in  the  same  manner  as  directed  in 
§  §  102  and  103  for  the  treatment  of  the  corresponding 
part  of  the  soil. 

e.  A  determination  of  humus  is  generally  unnecessary, 
but  if  desired,  can  be  conducted  as  directed  in  §  104. 

f.  A  determination  of  nitrogen  will  rarely  be  needed, 
but  may  be  made  in  the  usual  manner,  with  5-10  grms. 
of  the  marl. 

g.  Some  marls,  particularly  such  as  are  lich  in  clay,  and 
contain  but  little  sand,  are  much  more  efiective  after  hav- 
ing been  gently  ignited.  To  test  the  marl  in  this  respect, 
heat  it  to  a  low  red  heat  in  a  muffle,  with  free  access  of 
^ir,  and  then  make  an  aqueous  extract  of  the  ignited  mass 
by  treating  500  grms.  ot  it  with  2000  c.o.  of  distilled 
water,  with  frequent  agitation  during  a  cold  digestion  of 
48  hours.  Then  filter  off  "  1^  of  the  solution,  or  1600  c.c, 
for  the  determination  of  the  alkalies ;  evaporate  this  solu- 
tion to  dryness,  eliminate  silica  in  the  usual  manner,  and 
estimate    the    alkalies    in    the    filtrate    from     the    silica 

(§  93,  G-). 

Another  portion  of  100  grms.  of  the  ignited  marl  may 
be  treated  with  300  c.c.  of  concentrated  hydrochloric  acid 
in  the  cold,  in  the  manner  already  directed,  to  estimate 
phosphoric  acid,  and,  if  desired,  the  alkalies  again. 

h.  Analyses  of  the  green  sand  marl  of  New  Jersey. 
(Cook.) 

Carbonic  acid 2 

Lime 2.4  1.0 

M:i<?nesi:x 0.4  2.0 

Ferric  oxide 8.3  21.3 

Alumina 6.1  8.0 

Potasli 2.5  7.1 

Sulpliuric  acid 0.9  0.4 

Plio.sphoric  acid 1.4  1.3 

Silica  [soluble] 20.2  45.9 

Silica  [insoluble  sand] 49.9  4.0 

Water 7.1  8.1 

99.4  99.1 


§    1]0.       LIMESTOXE    AND    LIME.  209 

LIMESTONE  AND  LIME. 

llOt  a.  If  it  is  desired  to  examine  the  changes  that  a 
limestone  has  midergone  in  weathering,  or  to  ascertain 
what  it  contains  that  may  contribute  to  the  fertility  of 
the  soil,  it  should,  of  course,  be  taken  in  its  natural,  air- 
dry,  unignited  condition. 

Pulverize  it,  and  treat  from  150  to  300  grms.,  according 
to  the  proportion  of  clay  or  other  silicates  present,  Avith 
cold  and  hot  concentrated  hydrochloric  acid,  with  sul- 
phuric acid,  and  so  on,  in  the  manner  directed  for  the 
analysis  of  soils.  The  cold  hydrochloric  acid  dissolves 
all  the  carbonates,  commonly  all  the  phosphoric  acid,  but 
only  a  small  portion  of  the  alkalies,  even  if  a  considerable 
amount  of  these  is  present.  But  this  small  quantity  that 
is  taken  into  solution  should  be  determined,  and  the  esti- 
mation can  be  effected,  after  removal  of  the  silica,  in  the 
usual  manner  (Scheme  I.,  a  or  ^,  §  94). 

The  residue,  insoluble  in  cold  hydrochloric  acid,  is  of 
great  importance,  agriculturally  considered,  for  it  is  not 
seldom  rich  in  potassa,  and  it  should  be  examined  with 
the  aid  of  the  silt  analysis,  as  well  as  of  hot  hydrochloric 
acid,  sulphuric  acid,  and  hydrofluoric  acid  (§  §  101,  102, 
103).  In  one  case,  over  50"  ]„  of  potassic  feldspar  was 
found  in  the  sandy  insoluble  residue  of  a  dolomitic  lime- 
stone ;.in  another  case  little  but  pure  quartz. 

h.  By  "  burning  "  the  limestone,  itis  essentially  changed 
with  respect  to  the  solubility  of  its  constituents,  and  par- 
ticularly the  alkalies,  which  become  soluble  in  larger 
measure.  Therefore,  when  a  limestone  is  to  be  applied  to 
the  soil  after  being  burned,  it  should  be  burned  before 
being  analyzed  ;  this  may  be  accomplished  by  igniting  it 
in  a  Hessian  crucible  through  the  bottom  of  which  a  hole 
has  been  broken,  until,  after  cooling,  a  piece  of  it  falls 
completely  to  a  fine  powder  when  moistened  with  about 
a  third  of  its  weight  of  water. 


210  §    110.       A2fA.LYSIS    OF    SOILS    ANT>    EOCKS. 

1.  Ill  this  burned  limestone,  determine  the  alkalies 
soluble  in  water  by  treating  150  grms.  with  1500  c.c.  of 
distilled  water,  with  frequent  agitation  during  a  digestion 
of  24  hours.  Then  pour  off  1000  c.c.  of  the  supernatant 
liquid,  as  clear  as  possible,  filter,  if  the  liquid  is  not  per- 
fectly clear,  remove  silica  as  usual  (§  58,  a),  by  evapora- 
tion to  dryness  and  treatment  with  hydrochloric  acid, 
and  eliminate  the  alkalies  as  chlorides  (§  93,  G). 

2.  Digest  another  joortion  of  100  to  150  grms.  of  the 
burnt  lime,  according  to  its  richness  in  silicates,  48  hours 
in  tlie  cold,  with  tliree  times  its  weight  of  concentrated 
hydrocliloric  acid,  filter  the  mixture,  and  wash  the  resi- 
due, first  with  cold,  and  then  with  hot  water.  Determine 
phosphoric  acid  and  the  alkalies  in  this  solution  (Scheme 
I.,  §  94) ;  no  ferric  chloride  need  be  added. 

It  sometimes  happens  that  a  considerable  separation  of 
gelatinous  silica  renders  the  filtration  of  the  hydrochloric 
acid  solution  very  difiicult.  In  this  case,  evaporate  the 
whole  mixture  to  complete  dryness,  moisten  the  residue 
with  concentrated  acid,  let  it  stand  awhile,  boil  with  di- 
lute acid,  filter,  and  examine  this  filtrate  for  phosphoric 
acid  and  alkalies,  as  above.  The  solution  Avill  contain  all 
that  would  ordinarily  be  dissolved  by  both  cold  and  hot 
hydrocliloric  acid. 

Treat  the  residue,  insoluble  in  cold  hydrochloric  acid, 
with  hot  acid,  if  not  already  so  treated,  and  then  with 
sulphuric  and  hydrofluoric  acids  (§  §  101,  102,  and  103). 

e.  To  determine  whether  a  limestone  will  yield  good 
mortar  lime,  digest  4-5  grms.  with  dilute  hydrochloric 
acid,  evaporate  the  whole  to  dryness,  after  adding  a  few 
drops  of  nitric  acid,  boil  the  residue  with  acidified  water, 
filter,  wash,  ignite,  and  weigh.  A  good  limestone,  for 
this  purpose,  should  not  leave  more  than  5  to  10°  ]„  of  in- 
soluble matter. 

The  solution  may  be  examined  for  alumina,  ferric  oxide. 


§    110.       LIMESTONE    AXD   LIME.  211 

lime,  and  magnesia,  according  to  Scheme  I.,  §  94 ;  man- 
ganese need  not  be  noticed  unless  a  qualitative  analysis 
reveals  its  presence  in  considerable  quantity. 

A  determination  of  carbonic  acid  may  be  made  to  con- 
trol the  results  of  the  other  part  of  the  analysis. 

All  the  bases  found  should  be  calculated  as  carbonates 
in  making  up  the  final  statement. 

d.  To  determine  whether  a  limestone  will  make  a  good 
hydraulic  cement,  the  course  described  in  the  preceding 
paragraph  should  be  followed ;  but  the  alkalies  should  be 
determined  also,  and  the  residue,  insoluble  in  hydrochloric 
acid,  should  be  examined  with  the  aid  of  sulphuric  and 
hydrofluoric  acids  (§  §  102  and  103).  50-60  grms.  of  the 
stone  should  be  taken  for  treatment  with  hydrochloric 
acid.  And,  as  the  chemical  analysis  alone  will  not  furnish 
pei-fectly  safe  information  in  regard  to  the  fitness  of  the 
stone  for  the  purpose  in  question,  portions  of  it  should  be 
ignited  at  various  temperatures,  and  the  resulting  lime  in 
each  case  pulverized  and  made  into  little  balls  with  water, 
either  alone  or  with  sand,  and  tested  under  water,  to  see 
whether  it  hardens  properly. 

e.  If  the  cement  already  prepared  is  given  for  exami- 
nation, it  Avill  be  important  to  determine  the  amount  of 
gelatinous  silica  set  free  by  the  hydrochloric  acid,  as  well 
as  the  lime,  alumina,  and  alkalies.  20-25  grms.  of  sub- 
stance will  usually  answer  for  the  analysis,  since  the  stone 
is  rendered  more  soluble  by  the  ignition  that  is  required 
to  convert  it  into  cement. 

Boil  the  residue,  that  is  insoluble  in  hydrochloric  acid, 
with  sodic  carbonate  (§  58,  a^  2),  pulverize  what  is  in- 
soluble in  this  agent  very  finely,  and  treat  it  with  hydro- 
fluoric acid. 


212  §    111.       ANALYSIS    OP    SOILS    AXD    ROCKS. 

CLAY. 

111.  This  should  be  taken  for  analysis  in  its  natural, 
air-dried  condition,  and  examined  by  the  same  processes 
as  have  been  given  for  the  mechanical  analysis  of  soils, 
and  their  treatment  with  acids.  Different  clays  are  very 
differently  affected  by  these  agents. 

Conclusions  in  regard  to  their  agricultural  value  must 
be  based  upon  their  relative  solubility  in  the  acids  used, 
and  the  composition  of  the  part  that  is  soluble  in  hydro- 
chloric acid,  and  of  that  which  is  made  soluble  by  treat- 
ment with  sulphuric  acid. 

For  technical  purjioses  it  Avill  usually  answer  to  treat 
10-15  grms.  of  the  clay  with  6-8  times  its  weight  of  con- 
centrated sulphuric  acid,  evaporate  the  mixture  to  com- 
plete dryness,  exhaust  the  residue  w^ith  dilute  hydrochloric 
acid,  eliminate  silicic  acid  from  this  solution,  and  estimate 
alumina,  ferric  oxide,  manganese,  lime,  magnesia,  and  the 
alkalies,  according  to  Scheme  I.,  a  and  c,  §  94,  omitting 
the  estimation  of  phosphoric  acid,  and  consequently  the 
addition  of  ferric  chloride ;  determine  also  the  silica  solu- 
ble in  alkaline  carbonate  in  the  residue  that  is  insoluble  in 
hydrochloric  acid  above. 

Burnt  clay  may  sometimes  be  profitably  applied  as  a 
fertilizer,  or  an  amendment.  The  examination  of  such  a 
clay  should  be  conducted  in  the  same  manner  as  described 
for  burnt  marl  (§  109,/);  particular  attention  should  be 
paid  to  the  amount  of  alkalies  soluble  in  water,  and  in 
cold  and  hot  hydrochloric  acid. 

The  proportion  of  phosphoric  acid  is  not  usually  any 
larger  than  in  arable  soils. 


§    112.       FARM- YARD   MAXURE.  213 

CHAPTER  VI. 

FERTILIZERS. 

I. 

PRODUCTS    OF    THE    FARM-YARD. 
FARM-YARD  MANURE. 

112.  In  the  examination  of  farm-yard  manure,  the  part 
soluble  in  water,  and  that  which  is  insoluble  in  this  agent, 
should  each  be  examined  by  itself,  for  it  is  important  to 
know  the  relative  proportion  and  composition  of  these  two 
portions. 

To  procure  a  sample  of  the  manure,  take  several  small 
portions  from  different  parts  of  the  pile,  mix  them  all 
carefully  together,  breaking  up  the  lumps  while  working 
the  mass  over,  and  preserve  3-4  kilos,  for  examination. 

a.  Water. — Dry  1000  grms.  of  this  in  the  drying- 
chamber,  powder  the  residue  as  much  as  possible,  or  cut 
it  up  with  shears,  w^eigh  the  whole,  dry  about  50  grms., 
accurately  weighed,  at  100°  C,  and  calculate  the  loss  of 
weight  for  the  whole  1000  grms.  Grind  this  diied  sub- 
stance to  a  powder  in  a  steel  mill. 

b.  Organic  matter. — Ignite  6-8  grms.  of  this  powder 
with  the  usual  precautions,  including  the  determination 
of  carbonic  acid  and  coal  (§  91). 

c.  Carbonic  acid. — Determine  this  in  5  grms.  of  the 
powder  (§  60). 

d.  IVitrogen. — Determine  this  in  1  grm.  of  the  powder. 
The  small  amount  of  nitric  acid  in  the  manure  will  be  al- 
most completely  converted  into  ammonia  during  the  com- 
bustion, in  the  presence  of  so  large  a  proportion  of  car- 
bonaceous ororanic  matter.     The  nitrogen  in  the  amnionic 


214  §    112.       FERTILIZEES. 

carbonate,  that  is  volatilized  during  the  process  of  dry- 
ing, and  which  is  determined  in  the  aqueous  extract  of  a 
portion  of  the  original  manure,  should  be  added  to  that 
obtained  by  combustion  with  soda-lime,  in  order  to  get 
the  total  nitrogen. 

e.  Ammonia. — ^Determine  this  by  the  distillation  of 
15-20  grms.  of  the  dried  and  ground  manure,  with  1  grm. 
of  freshly  ignited  magnesia,  and  water,  and  the  estimation 
of  the  ammonia  in  the  distillate  by  titration  (§  47,  c). 

/.  Sulphur  aud  sulphuric  acid, — Determine  total  sul- 
phur in  the  manure  by  fusion  of  3-4  grms.  of  the  powder 
with  potassic  nitrate  (§  92). 

g.  Aqueous  extract  of  the  manure. — Pour  3000  c.c.  of 
water  over  a  second  portion  of  1000  grms.  of  the  fresh 
manure,  mix  the  whole  well  togetlier,  let  the  mixture 
stand  quietly  several  hours,  and  decant  the  supernatant 
liquid.  In  order  to  wash  the  residue  without  using  too 
much  water,  put  it  in  a  large  funnel,  which  is  stopped  in 
the  throat  with  asbestus,  and  below  with  a  cork,  press  it 
down,  pour  water  over  it,  and  work  the  whole  over  gently 
with  a  pestle  ;  after  a  time,  remove  the  cork,  and  let  the 
liquid  run  off,  and  repeat  the  operation  until  tlie  water 
that  passes  away  is  almost  colorless.  Reserve  the  residue 
in  the  funnel  for  further  treatment. 

Filter  the  whole  quantity  of  the  liquid  with  which  the 
fresh  manure  was  treated  through  linen,  make  the  volume 
of  the  filtrate  and  washings  up  to  6000  c.c,  and,  if  neces- 
sary, filter  again  through  paper. 

1*  Ammonic  salts. — Determine  volatile  ammonic  salts 
(ammonic  carbonate)  in  300-600  c.c.  of  the  aqueous  ex- 
tract, by  distilling  off  about  "I3  of  it  in  the  j^roper  appa- 
ratus (§  47),  without  adding  any  alkali,  and  titrate  the 
distillate  with  the  standard  sodic  solution  as  usual. 

Determine  7ion-volatUe  ammonic  salts  by  adding  1-2 
grms.  of  freshly  ignited- magnesia,  or  10-15  c.c.  of  milk  of 


§    112.       FAEM-YAKD    MANURE.  215 

lime  to  the  remainder  of  the  liquid  in  the  retort,  distilling 
off  ^la  of  the  water,  collecting  the  ammonia  in  the  usual 
manner,  and  titrating  the  distillate. 

The  total  amount  of  ammonia  in  the  aqueous  extract 
may  be  determined  also  by  Schlossing's  method  ;  evapo- 
rate 200  c.c.  of  the  liquid  down  to  50  c.c.  after  adding  a 
slight  excess  of  hydrochloric  acid,  and  proceed  with  this 
concentrated  solution  in  the  usual  manner  (§  47,  b). 

2.  Nitric  acid. — To  determine  this  in  the  aqueous  ex- 
tract, evaporate  500  c.c.  down  to  a  small  bulk,  and  pro- 
ceed with  this  concentrated  solution  according  to  Schloss- 
ing's method  (§  62,  a). 

3.  Total  amount  of  dry  substance  in  solution. — ^Evap- 
orate the  remainder  of  the  extract  to  dryness  in  a  weighed 
platinum  dish,  on  the  water-bath,  and  determine  the  total 
amount  of  matters  in  solution. 

4.  Organic  matter. — Ignite  3-4  grms.  of  this  residue, 
to  determine  organic  and  inorganic  matter  (§  91),  and 
determine  carbonic  acid  and  chlorine  in  the  ash  (§  60,  c). 

5.  Carbonic  acid.^ — ^Determine  this  in  2-3  grms.  of  the 
residue  obtained  in  3  (§  60). 

6.  Nitrogen. — ^Determine  this  in  1  grm.  of  the  residue 
obtained  in  3,  by  combustion  with  soda-lime  (§  85). 

7.  Chlorine. — This  may  be  partially  volatilized  in  the 
process  of  incineration ;  an  accurate  estimation  of  it,  there- 
fore, requires  its  determination  in  a  portion  of  the  aqueous 
extract  itself.  100  c.c.  of  this  maybe  taken,  or  0.5-1 
grm.  of  the  residue  obtained  in  3,  dissolved  in  water. 
Add  nitric  acid  to  the  solution,  in  slight  excess,  and  pre- 
cipitate chlorine  with  argentic  nitrate ;  treat  the  precipi- 
tate as  directed  for  the  case  in  which  much  organic  matter 
was  present  in  the  solution  (§  63). 

Instead  of  following  this  course,  a  small  portion  of  the 
residue  obtained  in  3  may  be  fused  with  potassic  nitrate 
before  precipitation  with  argentic  nitrate  (§  92). 


216  §    112.       FERTILIZERS. 

8.  Ferric  oxide,  etc. — Ignite  the  remainder  of  the 
residue  obtained  in  3,  dissolve  the  ash  in  hydrochloric 
acid,  eliminate  silica  by  evaporation  to  dryness,  and  exam- 
ine the  filtrate  from  the  silicic  acid  according  to  Scheme 
L,  §  94. 

A.  The  total  residue,  insoluble  in  water,  obtained  in  </, 
is  dried  in  the  steam-chamber,  exposed  to  the  air  24 
hours,  and  weighed  in  this  air-dried  condition  ;  then  cut 
up  the  fibrous  parts  of  it  with  the  shears,  and  grind  the 
whole  to  a  fine  powder  in  the  porcelain  mortar  or  steel  mill! 

1.  Water. — In  10  grms.  of  this  powder  determine  hy- 
groscopic water  by  heating  to  110°  C 

2.  Organic  matter. — Ignite  the  dry  residue  obtained 
in  «,  and  determine  the  loss  (§  91),  and  determine  car- 
bonic acid  and  chlorine,  if  desired,  in  the  ash. 

3.  Nitrogen. — To  determine  the  nitrogen  in  undecom- 
posed  organic  matter  in  the  manure,  a  part  of  which  might 
be  insoluble  in  water,  and  hence  found  here,  ignite  1-2 
grms.  of  the  powder  with  a  considerable  proportion  of 
soda-lime  (§  85). 

4.  Ferric  oxide,  etc. — Ignite  30-40  grms.  of  the 
powdered  insoluble  residue  in  a  platinum  dish,  and  in 
3-6  grms.  of  the  properly  prepared  ash  (§  123,  c),  accord- 
ing to  the  proportion  of  sand  present,  eliminate  silica  and 
sand,  and  analyze  the  remainder  according  to  Scheme  I. 
or  II, 


§    113.       URINE. 


217 


Analyses  of  farm-yard  manure  by  Yoelcker. 


Water 

Soluble  orgiinic  mattei-i 

Mineral  matter  soluble  in  water. 

Silica  (sola  ble) 

Calcic  phosphate,  3CaP04. 

Lime 

Maj^iiesia 

Potassa 

Soda 

Sodic  chloride 

Sulpliuric  acid 

Carbonic  acid  (and  loss). . . 


Insoluble  organic  matter^ , 

Mineral  matters  insoluble  in  water., 

Silica  (soluble) 

Silica  (insoluble,  and  sand)... 

Ferric  oxide  and  alumina 

Lime 

Magnesia 

Potixssa 

Soda 

Sulphuric  acid 

Phosphoric  acid 

Carbonic  acid  (and  loss) 


^Contains  nitroo-cn . 


Free  ammonia. . . 
Ammouiacal  salts 


Fresh. 


0.237 
0.299 
0.006 
0.011 
0.573 
0.051 
0.030 
0.055 
0.218 


0.964 
0.418 
1.120 
0.143 
0.099 
0.019 
0.061 
0.178 
0.484 


66.17 

2.48 


Rotted. 


1.54 
25.76 


0.254 
0.383 
0.117 
0.047 
0.446 
0.023 
0.037 
0.058 
0.106 


1.4^ 
1.010 
0.673 
1.667 
0.091 
0.045 
0.038 
0.063 
0.274 
1.295 


4.05 


100.00 

0.149 
0.494 
0.340 
0.880 


75.42 
3.71 


0.47 

12.82 


6.58 


100.00 

0.297 
0.309 
0.046 
0.057 


FRESH  ANIMAL  EXCREMENTS. 


URINE. 


118.  The  following  method  is  designed  more  particu- 
larly for  the  analysis  of  the  urine  of  herbivorous  animals, 
but  it  may  be  applied  in  the  examination  of  that  of  carniv- 
orous animals  and  man,  also. 

a.  Specific  Gravity. — Determine  this  in  the  usual  man- 
ner by  comparing  the  weights  of  equal  volumes  of  the 
urine  and  of  water  (§  34),  or  with  the  urometer,  a  species 
of  liydrometer  constructed  expressly  for  thig  purpose; 
10 


218  §    113.       FERTILIZERS. 

when  this  instrument  is  used,  all  foam  must  bo  carefully 
removed  from  the  surface  of  the  liquid,  by  filter  paper. 

A  difference  of  4°  C.  in  the  temperature  of  the  liquid 
usually  makes  a  difference  of  about  1°  in  the  reading  of 
the  urometer. 

The  specific  gravity  of  urine  ranges  between  1.01  and 
1.04. 

h.  Total  amount  of  dry  substance  in  solution. — De- 
termine this  by  evaporating  a  weighed  quantity  in  a  cur- 
rent of  dry  hydrogen  in  such  a  manner  as  to  estimate  the 
ammonia  that  is  expelled  at  the  same  time  (§  90,  d).  Take 
4-6  c.c.  of  the  urine,  accurately  weighed.  The  evapora- 
tion to  dryness  is  completed  in  4-5  hours. 

In  human  urine,  that  has  an  acid  reaction  due  to  acid 
sodic  phosphate,  the  ammonia  may  be  assumed  to  have 
been  derived  from  urea,  and  by  multiplying  the  amount 
of  it  by  1.765,  the  corresponding  amount  of  urea  will  be 
obtained.  But  in  the  urine  of  herbivorous  animals  the 
ammonia  resulting  from  this  decomposition  must  be  esti- 
mated by  the  difference  between  the  ammonia  set  free  on 
evaporation  to  dryness,  and  that  found  in  the  urine  by  di- 
rect determination.  Generally,  however,  these  quantities 
of  ammonia  are  very  small,  and  can  be  left  out  of  consid- 
eration. 

The  non-TOlatile  matter  in  this  residue  left  on  evapora- 
tion is  determined  by  evaporating  a  fresh  quantity  of 
100  c.c.  of  the  urine  in  a  platinum  dish,  and  igniting  the 
residue  (§  91,  1) ;  determine  carbonic  acid  in  the  ash  in 
the  usual  manner. 

c.  Carbonic  acid  (free  and  combined). — Determine  this 
in  two  portions  of  100  c.c.  of  the  fresh  urine.  To  one 
portion  add  baric  chloride  containing  ammonia  in  excess, 
and  to  the  other  baric  chloride  alone ;  heat  both  mixtures 
nearly  to  boiling,  collect  the  precipitates  on  dried  and 
weighed  filters,  wash  them,  and  dry  them  at  100°,  weigh, 


§  113.     rmxE.  219 

and  determine  carbonic  acid  in  1-2  grms.  of  each  precipi- 
tate in  the  usual  manner ;  the  first  precipitate  contains  the 
total  carbonic  acid,  the  second  only  the  combined. 

d.  Nitrogen. — The  residue  left  in  the  boat  in  h  may  be 
used  for  the  determination  of  nitrogen,  or  another  portion 
of  5-10  c.c.  of  the  urine  may  be  acidified  with  oxalic  acid, 
mixed  with  ignited  gypsum,  and  evaporated  to  dryness. 
In  the  former  case  this  second  residue  will  contain  only  so 
much  of  the  nitrogen  as  Avas  not  expelled  in  the  form  of 
ammonia  during  the  desiccation ;  in  the  latter,  the  oxalic 
acid  will  prevent  the  escape  of  any  nitrogen  as  ammonia. 
The  dry  substance  may  be  completely  rinsed  off  the  sides 
of  the  dish  with  some  of  the  soda-lime  used  in  the  com- 
bustion. 

Or,  this  method  of  Voit  may  be  used.  Weigh  out 
about  5  c.c.  of  the  urine,  mix  it  in  a  shallow  dish  with 
a  sufiicient  quantity  of  fine  quartz  sand  to  absorb  it  all, 
put  the  dish  under  the  receiver  of  an  air-pump,  and  ex- 
haust the  air ;  the  whole  becomes  quite  dry  in  a  few  hours 
and  may  be  pulverized  easily,  and  completely  loosened 
from  the  sides  of  the  dish  and  mixed  with  the  soda-lime. 

The  combustion  may  be  performed  in  a  short  combus- 
tion-tube and  very  rapidly,  without  fear  of  losing  any  of 
the  ammonia. 

e.  Actual  ammonia. — ^Determine  this  by  Schlossing's 
method  in  20  c.c.  of  the  urine,  after  filtration  to  remove 
slimy  or  sedimentary  matters  (§  47,  V).  In  the  fresh  urine 
of  horned  cattle,  the  actual  ammonia  does  not  amount  to 
more  than  0.009-0.01°  |„,  but  in  human  urine  it  ranges  as 
high  as  0.078  to  0. 143°  [. 

/.  Complete  analysis  of  the  ash. — Evaporate  200-500 
grms.  of  the  urine  to  dryness,  incinerate  the  residue,  and 
examine  the  ash  as  directed  in  Scheme  IV.,  §  94.  The  ash 
of  the  urine  of  herbivorous  animals  is  poor  in  alkaline 
earths,  and  8-10  grms.  will  be  required  for  their  determi- 


220  §    113.       FEKTILIZEIIS. 

nation.  In  the  urine  of  ruminants,  phosphoric  acid  is 
found  in  hardly  determinable  quantity,  while  in  that  of 
swine  and  often  of  calves,  it  is  present  in  larger  quantity, 
and  should  be  estimated. 

g.  Chlorine  and  urea. — These  are  determined  with  the 
aid  of  the  standard  solution  of  mercuric  nitrate.  The 
urine  must  first  be  freed  from  phosphoric  and  hippuric 
acids. 

Acidify  200  c.c.  with  nitric  acid,  boil  the  mixture  to  ex- 
pel the  carbonic  acid,  neutralize  the  nitric  acid  w4th 
freshly  ignited  magnesia,  and  cool  the  liquid  to  the  tem- 
perature of  the  room,  by  immersing  the  flask  in  cold  wa- 
ter ;  transfer  the  liquid  to  a  graduated  cylinder,  rinse  the 
flask  into  the  cylinder  and  bring  the  volume  of  its  con- 
tents to  220  c.c;  add  30  c.c.  of  an  aqueous  solution  of  fer- 
ric nitrate  of  such  a  degree  of  concentration  that,  with 
this  quantity  of  the  solution  added,  the  salt  will  be  shghtly 
in  excess ;  the  excess  may  be  recognized  by  a  weak  reac- 
tion of  the  solution  on  a  slip  of  filter  paper  soaked  in  a 
dilute  solution  of  potassic  ferrocyanidc ;  too  large  an  ex- 
cess of  the  ferric  salt  will  be  indicated  by  a  re-solution  of 
the  precipitate  that  was  formed  at  first,  on  its  addition ; 
filter  the  liquid  immediately  through  a  large,  dry,  ribbed 
filter,  and  to  150  c.c.  of  the  filtrate  add  50  c.c.  of  a  solu- 
tion of  baryta  mixed  with  a  little  calcined  magnesia,  filter 
again,  and  for  each  determination  of  sodic  chloride  and 
urea  take  15  c.c.  of  this  filtrate,  corresponding  to  9  c.c.  of 
urine. 

1.  Chlorine  (common  salt). — Acidify  exactly  15  c.c.  of 
the  liquid  with  a  drop  of  nitric  acid,  and  allow  the  stand- 
ard solution  of  mercuric  nitrate  to  flow  in  from  the  burette, 
with  constant  stirring  until  a  permanent  turbidity  ap- 
pears. A  mere  opalescent  appearance  of  the  liquid,  which 
may  be  presented  even  in  the  beginning,  is  easily  distin- 
guished from  the  cloudy  turbidity  which  is  the  real  indica- 
tion of  saturation. 


§    113.       UKIxN'E.  221 

Estimate  the  amount  of  sodic  chlorine  or  of  chlorine  on 
the  basis  of  the  standard  of  the  solution  already  determ- 
ined (§  86). 

2.  Urea. — In  a  second  portion  of  15  c.c.  of  the  liquid, 
proceed  to  determine  urea  with  tlie  same  standard  solution 
(§  86).  Subtract  from  the  total  amount  of  standard  so- 
lution required  the  amount  used  in  1,  and  also  make  the 
correction  required  for  dilution  of  the  solution. 

h.  Hippuric  acid. — Evaporate  200  c.c.  of  the  urine 
down  to  50  C.C.J  and  precipitate  the  acid  as  directed  in  § 
76.  It  may  be  well  to  first  digest  the  urine  with  animal 
charcoal  in  the  proportion  of  2  grms.  of  charcoal  to  10  c. 
c.  of  the  liquid,  in  order  to  decolorize  it. 

There  are  usually  only  traces  of  uric  acid  in  the  urine 
of  herbivora,  and  it  need  not  be  estimated ;  but  in  the 
urine  of  carnivora,  the  proportion  of  uric  acid  generally 
exceeds  that  of  the  hippuric. 

According  to  the  process  of  Meissner  and  Shepai  d,  for 
separating  these  two  acids,  evaporate  the  urine  until  it  be- 
gins to  crystallize,  add  so  much  absolute  alcohol  to  the  hot 
liquid  that  a  further  addition  causes  no  more  precipitation, 
let  the  mixture  cool,  and  filter  it ;  the  best  absolute  alcohol 
must  be  used,  and  it  must  not  be  spared,  else  succinic 
acid  may  remain  in  solution  with  the  hippuric  and  cause 
trouble.  Evaporate  the  alcoholic  solution,  at  first  in  a 
flask  on  the  water-bath,  until  all  the  alcohol  and  tlie  water 
are  expelled  and  only  a  brown  syrup  remains,  that  solidi- 
fies to  a  crystalline  mass  on  cooling ;  extract  this  mass, 
while  yet  warm  and  liquid,  with  ether  and  a  few  drops  of 
hydrochloric  acid  added  after  the  ether,  agitate  the  mix- 
ture violently,  and  repeat  the  process  two  or  three  times 
with  fresh  portions  of  ether.  If  the  alcohol  and  water 
were  not  carefully  removed  in  the  preceding  evaporation, 
some  of  the  urea  will  pass  into  this  ethorial  solution. 

Collect  all  the  etherial  extracts,  distil  off  most  of  the 
ether,  and  let  the  rest  evaporate  spontaneously  in  the  air. 


222  •  8  li; 


FERTILtZEILS. 


riippuric  acid  appears  then  in  the  form  of  liandsome 
crystals.  If  the  crystals  are  not  colorless,  or  they  are  not 
readily  formed,  dilute  the  residue,  left  by  the  evaporation 
of  the  ether,  with  water,  boil  the  mixture  with  lime-wa- 
ter, filter,  concentrate  the  colorless  filtrate,  and  jjrecipitate 
the  hippuric  acid  by  hydrochloric  acid  in  excess. 

i.  Phosphoric  acid. — 1.  This  may  be  determmed  di- 
rectly in  the  urine,  with  the  standard  uranic  solution. 
Filter  the  urine,  if  necessary,  add  5  c.c.  of  sodic  acetate 
to  50  c.c.  of  the  filtrate,  and  titrate  the  mixture  witli 
uranic  acetate  as  usual  (§  Gl,  c). 

2.  To  obtain  a  more  accurate  determination,  add  tlic 
magnesia  mixture  to  50  c.c.  of  the  clear  urine,  collect  and 
wash  the  precipitate  in  the  usual  manner,  dissolve  it,  with- 
out drying,  in  acetic  acid  in  not  too  great  excess,  di- 
lute the  solution  to  50  c.c.  with  water,  add  5  c.c.  of  the 
solution  of  sodic  acetate,  and  titrate  as  before,  with  the 
uranic  solution  (§  61,  c). 

3.  To  determine  tlie  phosphoric  acid  that  is  combined 
with  alkaline  earths  only,  to  100-200  c.c.  of  the  urine,  ac- 
cording to  its  strength,  add  ammonia  until  alkaline  reac- 
tion ensues,  let  the  mixture  stand  12  hours,  and  collect 
and  treat  the  precipitate  in  the  manner  described  in  2. 
In  another  precisely  equal  quantity  of  urine,  the  precipi- 
tate by  ammonia  is  ignited  and  weighed  ;  the  amount  of 
magnesic  pyrophosphate  in  this  mixture  may  be  estimated 
by  multiplying  the  amount  of  phosphoric  acid  in  it,  as  de- 
termined above,  by  2.1831,  subtracting  the  sum  of  the 
pliosphates  from  this  product,  and  multiplying  the  re- 
mainder by  2.5227.  If  it  is  desired  to  determine  lime  and 
magnesia  directly,  dissolve  the  mixture  of  the  phosphates, 
obtained  above  by  precipitation  ^ith  ammonia,  without 
drying  it,  in  as  small  a  quantity  of  acetic  acid  as  possible, 
precipitate  the  lime  by  ammonic  oxalate,  and  the  mag- 
nesia as  phosphate  again  by  excess  of  ammonia. 


§    114.       SOLID    EXCREMENTS.  223 

Tc.  Sulphuric  acid. — Heat  50-100  c.c.  of  the  urine,  add 
some  nitric  acid,  and  then  baric  chloride  in  slight  excess 
(§  59). 

I.  Sulphur* — To  determine  total  sulphur,  mix  50  c.c.  of 
the  urine  in  a  silver  crucible  with  solid  caustic  potash  and 
a  little  saltpetre;  evaporate  the  mixture  cautiously  to 
dryness,  ignite  the  residue  strongly  until  it  is  quite  white, 
exhaust  it  with  water,  and  determine  sulphuric  acid  in  the 
filtered  solution,  in  the  usual  manner. 

m.  Carbon  and  Hydrogen. — Absorb  10  c.c.  of  the  urine 
by  fine  quartz  sand  that  lias  been  previously  boiled  with 
acid,  washed,  and  ignited,  dry  the  mixture,  and  bnrn  it 
with  plumbic  chromate.  (See  Fresenius's  Quantitative 
Analysis.) 

SOLID  EXCREMENTS. 

114.  The  solid  excrements  of  the  herbivora  are  exam- 
ined by  almost  precisely  the  same  methods  as  are  given 
for  the  analysis  of  fodder  (§  129). 

In  the  determination  of  woody  fibre,  owing  to  the  pres- 
ence of  resinous  matters  it  is  often  necessary  to  boil  the 
substance  with  alcohol  before  treating  it  with  dilute  acid 
and  alkali. 

Microscopic  examinations  are  often  useful  in  the  exami- 
nation of  these  excrements,  in  order  to  ascertain  what 
parts  of  the  plants,  that  were  consumed  as  fodder,  remain 
undigested.  For  this  purpose,  it  is  well  to  knead  a  por- 
tion of  the  substance  in  a  linen  bag  under  cold  water  un- 
til the  latter  is  no  longer  made  turbid.  Starch,  crystals 
of  difficultly  soluble  salts,  and  grains  of  sand,  may  be 
looked  for  in  the  sediment  deposited  from  the  water  used 
in  washing,  after  long  standing,  while  sugar,  gums,  lactic 
acid,  etc.,  may  be  sought  for  in  the  solution ;  the  residue 
in  the  bag  may  be  examined  with  the  microscope,  with  or 
without  previous  boiling  with  alcohol  to  remove  resinous 
matters. 


224  §    115.       FERTILIZERS. 

n. 

COMMERCIAL  CONCENTRATED  MANURES. 


115.  The  determinations  of  phosphoric  acid,  potassa,  and 
-nitrogen,  are  the  most  important  in  the  examination  of 
these  manures. 

a.  The  method  first  recommended  by  Pincus  for  esti- 
mating phosphoric  acid  by  means  of  a  standard  solution 
of  uranic  acetate  can  be  applied  in  the  analysis  of  guanos, 
bone-meal,  bone-black,  bone-ash,  and  most  of  the  super- 
phosphates, so  long  as  but  little  ferric  oxide  or  alumina  is 
present.  The  method  deserves  to  be  generally  followed, 
for  it  is  quickly  executed  and  sufficiently  accurate,  and 
because  it  is  desirable  that  all  estimations  of  phosphoric 
acid,  in  the  numerous  forms  in  which  it  is  presented  to  the 
public,  should  be  made  according  to  a  common  plan. 

The  preparation  of  the  standard  solution  and  the  man- 
ner of  conducting  the  analysis  have  been  already  describ- 
ed (§  61,  c). 

For  the  determination,  50  c.c.  of  the  solution  to  be  test- 
ed are  generally  taken,  and  10  c.c.  of  the  solution  of  sodic 
acetate  added.  If  the  quantity  of  the  precipitate  that  is 
formed  on  the  addition  of  this  reagent  and  boiling  is  quite 
small,  it  may  be  filtered  out,  washed,  dried,  and  ignited ; 
the  residue  may  be  regarded  as  ferric  phosphate,  FePO^, 
containing  47.02°|  „  of  phosphoric  acid  (PoO J.  The  volu- 
metric process  is  carried  out  Avith  the  filtrate  from  this 
precipitate.  If  the  precipitate  of  ferric  phosphate  is  not 
slight,  a  gravimetrical  process  is  safer  (§  93,  II). 

The  volumetric  process,  under  suitable  circumstances, 
gives  results  that  are  within  1  mgr.  of  the  trath. 


§    115.       COMMERCIAL    CONCEXTRATED   MANURES.     225 

In  case  a  large  quantity  of  phosphoric  acid  is  present, 
or  much  free  acid,  10  c.c.  of  the  acetate  may  not  be  suf- 
ficient to  saturate  all  this  acid  with  soda.  The  brown 
color  will  appear,  then,  before  all  the  phosphoric  acid  is 
precipitated;  but  it  is  diffused  through  the  entire  drop, 
and  does  not  present  a  well-defined  brown  zone  where  the 
drop  of  the  test  solution  and  of  the  ferrocyanide  come. to- 
gether; in  this  case  add  5  c.c.  more  of  sodic  acetate,  and 
it  will  be  found  that,  in  case  free  mineral  acid  was  present, 
more  of- the  uranic  solution  must  be  added  before  the 
brown  color  appears.  In  order  to  be  sure  in  regard  to 
this  matter,  it  will  always  be  well,  after  having  reached 
the  point  of  saturation,  to  add  5  c.c.  more  of  sodic  acetate, 
heat  the  mixture  to  boiling,  and  test  a  drop  of  the  solu- 
tion with  the  ferrocyanide.  If  a  brown  color  appears,  the 
result  first  obtained  was  correct.  Even  30  c.c.  of  sodic 
acetate  may  be  added  without  sensibly  impairing  the 
accuracy  of  the  work. 

h.  The  examination  for  potassa  may  be  conducted  ac- 
cording to  either  of  the  methods  described  in  §  93,  G. 
The  third  method,  in  which  platinic  chloride  is  used  to 
separate  potassa  from  the  alkaline  earths,  is  more  particu- 
larly applicable  in  the  examination  of  the  native  potash 
salts,  of  which  such  extensive  beds  have  been  discovered 
in  Germany,  and  from  which  large  quantities  are  taken  for 
agricultural  purposes. 

c.  The  determination  of  the  nitrogen  is  always  made  by 
combustion  with  soda-lime  (§  85). 

d.  Fresenius  {Quantitative  Chemische  Analyse^  894) 
gives  the  following  good  plan  for  stating  the  results  of  the 
analysis  of  a  superphosphate ;  a  similar  plan  can  be  fol- 
lowed, with  such  variations  as  may  be  necessary  in  each 
particular  case,  in  stating  the  result  of  the  analysis  of  any 
commercial  fertilizer. 


10* 


226 


115.       FERTILIZERS. 


Eiisily 
soluble 

iu 
Aviitcr. 

Diffl- 

cultly 
soluble 

ill 
water. 


Pliosphoric  acid,  H3PO4 

Li"^«     .         1      united 
Ma<rncsia 


ncsia 

i  FeiTic  oxide  f 

[  Potassa  J 

r 

Calcic  sulphate 
(CaS04,  2aq.) 

I 


with 
the  PoOs 


Soluble 
iu  acids. 


Phosphonc  acid 
Lime  |      united 

Magnesia       V       with 
[  Ferric  oxide  )    the  acid 
Insol. 
in  acids. 
Volatile    matter 

nition 

Water  expelled  at  100°  C 


Clay  and  saud 

expelled    on    ig- 


16.15:cont.  P206[anhyd] 
0.5 


42.00 

2.19 
1.01 

2.49 


6.51 
29.15 
100.00 


cont.  PijOs  [anhyd] 


contain'^  nitrogen 


P.O5 

11.7 


2.19 


0.41 
l37890:4i 


N. 


TARIFF  OF  PRICES  OF  COMMERCIAL  FERTILIZERS. 


c.  In  1857,  A.  Stockhardt,  of  Tharand,  published  a 
tariff  of  prices  of  commercial  fertilizers,  with  the  aid  of 
Avhicli,  in  a  very  simple  manner,  the  cost  of  the  mannre 
could  be  compared  with  its  real  value ;  in  this  tariff,  the 
estimation  of  the  money  value  of  each  of  the  three  im- 
portant constituents  of  these  fertilizers  in  general,  was 
b:ised  upon  the  price  that  would  have  to  be  paid  for  it  in 
other  and  also  commercial  forms,  containing  a  known  and 
often  guaranteed  proportion  of  tlie  substance.  The  per 
cent  composition  of  a  fertilizer  being  known,  the  j^ur- 
chaser  could  then  tell,  on  consulting  the  tariff,  whether  he 
Avas  required  to  pay  any  more  for  the  number  of  pounds  of 
nitrogen  or  phosphoric  acid  in  100  pounds  of  the  article 
lie  was  buying,  than  he  would  have  to  pay  for  the  same 
number  of  pounds  of  nitrogen  in  the  form  of  sulphate  of 
ammonia,  from  the  gas-works,  for  example,  or  of  phos- 
phoric acid  in  tlie  bone-black  of  the  sugar  refiners. 

A  greatly  improved  form  of  this  tariff,  which  was  put 
out  by  Stockhardt  in  1866  ( Chemische  Ackersmcmn,  1866, 


115. 


TARIFF    OF    PRICES    OF    FERTILIZER- 


227 


226);  is  given  below,  with  the  prices  estimated  in  gold^QT 
pound. 

Tlie  editor  greatly  regrets  that  he  has  not  had  the  time 
or  the  opportunity  to  make  a  careful  examination  of  the 
various  forms  in  which  nitrogen,  phosphoric  acid,  and  pot- 
ash, are  to  be  had  in  this  country,  so  that  this  tariif  miglit 
be  conformed  therewith,  and  answer  the  same  purpose  for 
the  American  farmer  that  the  original  one  does  for  the 
farmers  throughout  Germany.  But,  nevertlieless,  the 
values  allowed  for  these  three  substances  in  the  tariff  as 
it  stands  are  not  far  out  of  the  way.  Prof  Johnson  {Be- 
port  to  the  Secretary  of  the  State  Board  of  Agriculture, 
0)1  Commercial  Manures,  April,  1869)  gives  the  following 
values  ill  gold:  potash,  4  cents;  soluble  phosplioric  acid, 
12|-  cents;  insoluble,  4^  cents;  nitrogen,  IT  cents.  The 
mean  of  the  four  values  of  nitrogen  in  Stockhardt's  tariff 
is  17.9  cents. 

Prof.  Johnson  says  very  truly  in  the  same  report,  "  The 
farmer  will  not  often  err  in  refusing  to  lay  out  his  money 
for  any  article  whose  cost  much  exceeds  the  calculated 
value,"  with  reference  to  his  own  tariff;  and  the  same- may 
as  well  be  said  of  the  scale  of  prices  adopted  in  this  work. 


Form  in  which  the  substance  exists  in  the  fertilizer. 

Phosplioric  acid,  soluble  in  water,  as  in  superphosphate 

"  "in  Peruvian  guano ,    

"  "      in  steamed  bones  finely  ground,  in  rape  cake, 

poudrette,  etc 

"  "      in  Baker  guano 

"            "      in  coarse  l)one  meal,  fresh  humanurine,  etc.. 
"            "      in  coarse  broken   bones,  fresh  human  excre- 
ments, stable  manure,  etc 

Potash,  as  potassic  sulijluite , 

"        as  potassic  chloride  and  in  other  forms, ■. . 

Nitrogen,  easily  soluble,  or  in  compounds  that  are  readily  de- 
comx)osed,  as    ammonia,    nitrates,    dried    blood, 

meat,  urea,  etc 

"         in  finest  bone  meal,  poudrette,  etc 

"         in  coarse  bone  meal,  rape  meal,  horn  meal,  wool  dust, 

fresh  human  urine,  etc 

"         in  coarse  broken  bones,  horn   shavings,  Avoolen  rags, 
fresh  hura;ui  excrements,  stable  manure,  etc 


Price 
@lb. 


in  gold. 

%  .12^ 

.10 

.083^ 
.07K 
.07 

.05K 

My, 

.05X 


.23 

.16X 
.V6% 


228  §    116.       FEliTILIZEES. 

Accordiug  to  this  tariff,  the  money  value  of  100  pounds  of  the  super- 
phosphate whose  composition  is  given  above,  would  be  estimated  as 
follows : 

11.7  lbs.  soluble  phosphoric  acid  @  12}^  cts.        $1.46 

2.19  "  insoluble        "  "     "    7>J    "  .32 

.41  "  nitrogen  "  ig)^    "  .08 

61.86 

The  value  of  a  ton  of  2000  pounds,  at  the  same  rate,  would  be  $37.20 
in  gold. 

BONE-MEAL. 

116.  Bone-meal,  as  found  in  commerce,  is  prepared 
either  from  nearly  or  quite  fresh  bones,  from  bones  that 
have  been  exposed  to  the  air  for  some  time,  or  from  those 
that  have  been  steamed  or  boiled ;  the  first  kind  contains 
much  fat  and  gelatine,  and  is  usually  quite  coarse ;  the 
third  kind  has  lost  nearly  all  its  fat  and  much  of  its  gela- 
tine, and  is  quite  fine ;  while  the  second  occupies  a  position 
between  the  other  two  in  all  respects. 

a.  Water. — ^Desiccate  about  5  grms.,  if  of  the  common 
kinds  of  steamed  bone-meal,  at  100°. 

h.  IVon-TOlatilc  matter. — Ignite  the  dried  residue  in  a 
and  treat  the  ash  with  ammonic  carbonate,  to  restore  car- 
bonic acid  that  was  expelled  by  heat  (§  91,  d), 

c.  Nitrogen. — Burn  0.5-0.8  grms.  of  the  finely  powder- 
ed meal  with  soda-lime  (§  85). 

cl  Phosphoric  acid. — Dissolve  3-4  grms.  of  the  ash 
obtained  in  h  in  as  little  nitric  acid  as  possible,  with  the 
aid  of  heat;  filter  the  solution  into  a  250  c.c.  flask,  wash 
the  sandy  insoluble  residue,  ignite,  and  weigh  it.  Fill  the 
flask  with  distilled  water  up  to  the  250  c.c.  mark,  mix  its 
contents  well  togetlier,  and  determine  phosphoric  acid  in 
50  c.c.  of  this  solution,  with  the  standard  uranic  solution 
(§  115,  a).  In  order  to  saturate  the  free  acid,  it  will  be  well 
to  add  20  c.c.  of  the  sodic  acetate.     If  a  coarse,  splintery 


§    116.       I30XE-MEAL.  229 

bone-meal  is  under  examination,  a  larger  quantity,  about 
50  grms.,  should  be  incinerated  in  order  to  get  the  ash  for 
treatment  with  acid. 

e.  Complete  analysis  of  the  ash. — Treat  a  portion  of 
the  solution  obtained  in  d  according  to  Scheme  IV.,  §  91, 
taking  50-100  c.c.  for  a  and  the  same  for  h.  This  exami- 
nation is,  in  genera],  unnecessary,  if  the  only  object  of  the 
analysis  is  to  determine  the  agricultural  value  of  the 
article. 

f.  Fat. — Exhaust  a  weighed  quantity  of  the  finely  pul- 
verized meal  with  ether,  dry  the  residue  at  125°  C,  and 
count  the  loss  as  fat  (§  87). 

g.  Gelatine. — The  gelatinous  substances  may  be  esti- 
mated by  the  difference  between  the  total  loss  on  ignition 
and  the  sum  of  the  water  and  fat. 

A.  Fineness  of  division  of  the  meal. — The  value  of 
bone-meal  depends  not  only  upon  its  chemical  composition, 
but  also  upon  the  fineness  of  the  powder. 

To  test  the  substance  in  this  respect,  it  should  be  passed 
through  sieves  of  difierent  degrees  of  fineness;  and  it  is 
important  that  all  chemists  should  use  sieves  of  the  same 
kind,  so  that  the  results  obtained  by  different  persons  can 
be  compared  with  each  other. 

Wolff  recommends  the  use  of  the  three  finest  sieves  of 
the  set  made  by  Hugershoff,  in  Leipzig,  the  first  of  which 

(I)  has  1089  meshes  in  a  square  centimetre,  the  second 

(II)  484  meshes,  and  the  third  (III)  256.  The  residue, 
tliat  will  not  pass  through  the  coarsest  sieve,  should  be 
examined,  in  order  to  see  whether  it  is  made  up  largely 
of  grains  which  would  pass  through  a  little  coarser  sieve 
still,  or  of  large  splinters. 

One  bone  meal  of  excellent  quality,  analyzed  by  Wolff, 
contained  60°!,  of  No.  L,  20°|„  of  No.  II.,  and  lO'l^of 
No.  III. 


230  §    117.       FERTILIZERS. 

BONE-BLACK,  BONE-ASH,  PHOSPHORITE. 

117.  A.  J3one-black,  after  it  has  been  used  by  the  sugar 
refiners,  usually  comes  into  the  market  as  a  manure.  Pul- 
verize 30-40  grms.  of  it  for  examination. 

a.  Water. — Desiccate  3-4  grms.  for  a  considerable  time 
at  150°  C. 

b.  Non-volatile  matter.— Ignite  the  dried  substance 
obtained  in  a,  and  treat  the  residue  with  ammonic  car- 
bonate, to  restore  carbonic  acid  expelled  during  the  igni- 
tion (§  91). 

c.  Carbonic  acid. — Estimate  this  in  3  grms.  (§  60). 

cl  Nitrogen.— Burn  0.5  to  0.8  grm.  with  soda-lime 
(§  85). 

e.  Phosphoric  acid,  etc. — Digest  the  contents  of  the 
flask  in  c,  after  adding  a  little  more  nitric  acid,  several 
hours  on  tlie  water-bath  ;  filter  the  liquid  into  a  250  c.c. 
flask,  Mash  the  residue  with  hot  water,  dry  it  at  150°, 
weigh,  ignite,  and  weigh  again.  The  loss  on  ignition  gives 
approximately  the  amount  of  charcoal,  and  the  residue 
left  after  icjnition  is  to  be  considered  as  scmd,  thouirh  it 
may  be  tested  with  nitric  acid  to  see  whether  any  more 
is  soluble. 

Dilute  the  contents  of  the  flask  to  250  c.c,  mix  all  parts 
of  the  solution  well  together,  and  determine  phosphoric 
acid  in  50  c.c.  with  the  uranic  solution  (§  115,  a). 

/.  Complete  analysis  of  the  ash.— Treat  a  portion  of 
the  solution  obtained  in  <?,  or  a  solution  obtained  in  the 
same  manner,  as  directed  in  Scheme  IV.,  §  94,  taking  100 
c.c.  for  a  and  the  same  for  b. 

[/.  Chlorine  may  be  determined  in  a  portion  of  the  so- 
lution obtained  in  e,  by  precipitation  with  argentic  ni- 
trate (§  63). 

h.  Calcic  hydrate. — It  is  sometimes  desirable  to  de- 
termine this  in  the  bone-black.     Moisten  a  portion  of  the 


§    117.       BOXE-BLACK,    BONE-ASH,    PHOSPHORITE.        231 

oriijinal  substance  witli  a  solution  of  ammonic  carbonate. 


evaporate  the  mixture  very  carefully  to  dryness  in  a  cov- 
ered crucible,  repeat  the  operation  several  times,  and  ig- 
nite, finally,  to  a  dull  red  heat,  not  strong  enough  to  burn 
the  coal.  Determine  carbonic  acid  in  this  residue ;  the 
diiference  between  the  quantity  found  here  and  in  c  repre- 
sents an  equivalent  quantity  of  calcic  hydrate  or  caustic 
lime,  CaO,  H^O. 

B.  Bone-ash  should  be  treated  as  directed  for  the  ash 
of  bone-meal,  with  tliB  addition  of  determinations  of 
moisture  and  of  carbonic  acid,  for  the  purpose  of  estimat- 
ing the  calcic  carbonate. 

C.  Phosphorite^  coproUtes. — Phosphorite,  nnd  other 
minerals  containing  phosphoric  acid,  are  usually  mixed 
with  oxides  of  iron  and  alumina  to  such  an  extent  that 
the  acid  cannot  be  determined  volumetrically. 

a.  Phosphoric  acid. — To  determine  this  alone,  Freseni- 
us  gives  the  following  directions.  {Fresenlus'^s  Zeitschrift^ 
6,  404). 

Heat  about  0.5  grm.  of  the  finely  ptilverized  minei'al  in 
a  small  flask  about  an  hour  on  the  water-bath,  with  8-10 
c.c.  of  concentrated  (fuming)  hydrochloric  acid,  and 
evapornte  the  mixture  to  dryness  in  the  usual  manner  for 
eliminating  silica  (§  58,  «,  1 ) ;  moisten  the  residue  with  2 
c.c.  of  hydrochloric  acid,  add,  after  a  short  time,  10  c.c. 
of  concentrated  nitric  acid  (Sp.  Gr.  1.2),  dilute  w4th 
Avater,  filter  and  wash  the  insoluble  residue ;  evaporate  the 
filtrate  and  washings  almost  to  dryness,  dissolve  the  resi- 
due in  5  c.c.  of  nitric  acid,  transfer  the  solution  to-  a  beak- 
er, rinse  out  the  evaporating  disli  with  a  little  water,  and 
then  wnth  the  solution  of  ammonic  molybdate ;  add,  in 
all,  150-200  c.c.  of  this  reagent,  and  proceed  with  the 
elimination  of  the  acid  as  directed  in  §  61,  h. 

h.  Complete  analysis. — ^Digest  5-10  grms.  of  the  well- 
pulverized  mineral  with  hydrochloric  acid,  filter  out  the 


232  §    118.       FERTILIZEllS. 

insoluble  substance,  dry  it,  boil  it  repeatedly  with  sodic 
carbonate,  to  dissolve  out  the  silicic  acid  (§  58,  a,  2),  and 
treat  this  insoluble  residue  with  6-8  times  its  wefght  of 
sulphuric  acid  to  decomj)ose  the  clay,  as  directed  under 
soil  analysis  (§  102).  Evaporate  the  solution  in  hydro- 
chloric acid  obtained  above  to  dryness,  and  eliminate  and 
weigh  the  silica  (§  58,  a,  1),  and  examine  the  filtrate  from 
the  silica,  as  directed  in  Scheme  I.,  except  that  manganese 
need  not  be  determined,  unless  a  qualitative  test  reveals 
its  presence  in  notable  quantity. 

GUANO. 

118i  A.  Peruvian  cr  other  ammoniaoal  guanos. — 
Pulverize  200-500  grms.  until  the  whole  will  pass  through 
a  tolerably  fine  sieve. 

a.  Water. — Estimate  this  in  1-2  grms.  in  such  a  manner 
as  to  collect  tlie  ammonia  that  is  expelled  at  the  same 
time  by  the  heat  (§  90,  d).  The  amount  of  ammonia 
given  off  is  usually  from  1-2"  |^  of  the  weight  of  the  guano. 

h.  Kon-VOlatilC  matters. — Ignite  6-8  grms.  carefully  in 
a  platinum  crucible  (§  91). 

c.  Nitrogen. — Burn  0.5  grm.  with  soda-lime.  The  mix- 
ture should  be  made  as  quickly  as  possible  in  the  tube, 
and  the  bulbed  tube  attached  immediately,  to  prevent  any 
loss  of  ammonia  (§  85,  h). 

d.  Actual   ammonia. —  Determine  this  in   1   grm.   by 

Schlossing's  process  (§  47,  ^>). 

e.  Phosphoric  acid,  etc. — ^Digest  the  ash  obtained  in  h 
with  nitric  acid,  filter  out  the  sand^  wash,  ignite,  and 
weigh  it,  and  dilute  the  filtrate  to  250  c.c. 

Determine  phosphoric  acid  in  50  c.c.  of  this  filtrate,  by 
th3  volumetric  method  (§  115,  a). 

For  another  method  of  estimating  phosphoric  acid  alone, 
mix  1  part  of  guano  (1-2  grms.)  with  1  part  of  sodic  car- 


§  118.     gua:j^o.  233 

bonate  and  1  of  nitre,  fuse  the  mixture  carefully,  dissolve 
the  residue  in  water,  and  evaporate  the  solution  to  dryness 
on  the  water-bath ;  treat  this  residue  with  hydrochloric  acid 
and  water,  as  in  eliminating  silicic  acid  (§  58,  «,  1) ;  filter, 
add  ammonia  to  the  filtrate  until  it  is  in  slight  excess,  then 
acetic  acid  until  the  calcic  phosphate  precipitated  by  the 
ammonia  is  dissolved ;  and  then,  without  filtering  out  the 
small  amount  of  ferric  phosphate,  determine  phosphoric 
acid  by  the  volumetric  method.     (Fresenius.) 

/  Complete  analysis. — Treat  a  portion  of  the  solution 
obtained  in  c,  or  one  obtained  in  like  manner,  after  elimi- 
nation of  silicic  acid,  according  to  Scheme  lY.,  §  94. 

cj.  Solubility  in  water. — Heat  10  grms.  of  the  powdered 
guano  with  200  c.c.  of  water,  filter  at  once  through  a 
weighed  filter,  wash  the  contents  of  the  filter  with  hot 
water,  as  long  as  the  water  has  any  yellow  color  and 
leaves  a  residue  when  evaporated ;  dry  and  weigh  the  in- 
colublo  residue.  Subtract  the  sum  of  the  water  and  the 
insoluble  substance  from  the  total  wei2:ht  of  the  miano, 
and  the  remainder  will  be  the  soluble  matter ;  and,  if  the 
insohible  residue  is  ignited  and  the  ash  weighed  and  sub- 
tracted from  the  total  amount  of  ash,  the  amount  of  solu- 
ble non-volatile  matters  will  be  given  by  the  remainder. 
(Fresenius.) 

A.  Uric  acid. — Digest  the  part  of  the  guano  that  is  in- 
soluble in  water  with  a  weak  solution  of  soclic  hydrate ; 
filter  the  mixture,  precipitate  the  uric  acid  in  the  filti-ate 
with  hydrochloric  acid,  and  proceed  as  directed  in  §  75, 
with  the  washing  of  the  precipitate. 

i.  Oxalic  acid, — Expel  the  carbonic  acid  from  a  weigh- 
ed portion  of  the  guano  with  sulphuric  acid,  neutralize 
the  excess  of  acid  with  sodic  hydrate  entirely  free  from 
carbonic  acid,  and  estimate  oxalic  acid  with  sulphuric  acid 
and  manganic  binoxide  (§  69). 

h.  Marks  of  a  ^ood  Peruvian  guano.— It  forms  a  loose, 


234  8  119. 


FERTILIZERS 


yelloAvisli-browii  powder  mixed  with  soft  lumps  of  various 
sizes,  which,  when  broken,  exhibit  white  veins  on  the 
fractured  surface,  or  sometimes  a  foliated  crystalline  ap- 
pearance. 

If  a  small  quantity  is  heated  with  a  few  drops  of  dilute 
nitric  acid  and  the  mixture  is  evaporated  to  dryness  at  a 
gentle  heat,  a  fine,  j^urple-red  colored  residue  is  left,  indi- 
cating the  i:)resence  of  uric  acid  (§  75). 

It  gives  a  good  reaction  for  ammonia  with  sodic  hydrate 
or  lime. 

By  digestion  with  water,  about  half  is  dissolved,  form- 
ing a  dark-yellow  solution;  if  the  guano  is  poor,  a  hght- 
yellow  solution  is  obtained.  This  solution  gives  the  usual 
reactions  for  ammonia,  lime,  magnesia,  and  sulphuric  acid. 

It  loses  60-70"!  „  Avhen  ignited,  and  leaves  a  grayish- 
white  ash  that  evolves  but  little  carbonic  acid  when  treat- 
ed with  nitric  acid,  and  leaves  but  from  1-3° |  „  of  matters 
insoluble  in  acid,  and  contains  5-10"  |„  of  fixed  alkaline 
salts. 

Baker  gucino^  and  other  phosphatk  guanos. — These 
arc  examined  in  the  same  manner  as  the  Peruvian  guano, 
except  that,  since  they  contain  but  a  very  small  propor- 
tion of  nitrogen  and  alkaline  salts,  the  determination  of 
phosphoric  acid  alone  answers  for  the  estimation  of  their 
agricultural  value.  This  may  generally  be  made  by  the 
volumetric  process. 

SUPERPHOSPHATES. 

119.  These  are  generally  mixtures  of  calcic  sulphate, 
calcic  chloride,  tricalcic  phosphate,  ferric  phospliate, 
monocalcic  phosphate,  organic  matters  containing  nitro- 
gen,.coal  and  water. 

Mix  the  sample  well  together,  breaking  up  all  the  lumps 
between  the  fingers  or  in  the  mortar. 

a.  Water. — Desiccate  3-4  grms.  for  a  considerable  time 
at  150-160°  C.  (§  90). 


§    119.       SUPERPHOSPHATES.  235 

h.  Non-VOlatilc  matters. — Ignite  the  dry  residue  ob- 
tained in  a  (§  91). 

c-  Nitrogen. — This  should  be  determined,  in  case  the 
])hosphate  was  prepared  from  Peruvian  guano  or  bone- 
meal,  or  it  is  claimed  that  it  contains  nitrogenous  matter. 
Ignite  0.5-1  grm.  with  soda-lime. 

d.  Actual  ammonia. — Determine  this,  if  present,  by 
Schlossing's  process,  in  1-2  grms.  (§  47,  h). 

e.  Phosphoric  acid. — The  value  of  a  superphosphate 
depends  chiefly  upon  the  amount  of  phosphate  that  it  con- 
tains that  is  soluble  in  water,  and,  when  tiie  article  was 
prepared  from  bone-black,  bone-ash,  phosphorite,  or  Baker 
guano,  the  determination  of  soluble  phosphate  suffices  for 
the  estimation  of  its  value.  But  when  made  from  steamed 
bones,  wholly  or  in  part,  there  is  commonly  from  5-0"  1^  of 
insoluble  phosphate  which  should  be  taken  into  account. 
It  appears  that  sometimes  the  proportion  of  soluble  phos- 
phate diminishes  when  the  article  is  kept  for  a  long  time ; 
if,  therefore,  an  unexpectedly  small  amount  is  found,  a 
determination  of  the  insoluble  phosphate  should  be  made 
also,  in  order  to  estimate  fairly  the  value  of  the  fertilizer. 

1.  To  estimate  the  sohihle  phosphate^  triturate  10  grms. 
of  the  well-mixed  sample  with  200-300  c.c.  of  water,  ap- 
plying pressure  enough  with  the  pestle  to  break  up  the 
lumps,  but  not  to  pulverize  the  hard  grains ;  let  the  mix- 
ture stand  some  time,  pour  oif  the  clear  supernatant  liquid 
through  a  filter,  and  repeat  the  exhaustion  with  water  as 
long  as  an  acid  reaction  is  communicated  to  a  fresh  por- 
tion ;  finally,  put  the  whole  insoluble  residue  on  the  filter, 
dry  it  at  100"",  and  weigh  it ;  bring  the  volume  of  the 
aqueous  extract  to  1000  c.c. 

Determine  phosphoric  acid  by  the  volumetric  method 
in  100  c.c.  of  this  solution,  first  precipitating  and  filtering 
out  the  fetric  phosphate,  if  but  a  small  quantity  is  formed, 
and  dry  and  w'eigh  this  precipitate ;  47.02"  |„  of  it  is  phos- 


236  §    119.       FERTILIZERS. 

phoiic  acid.  If  the  superphosphate  was  made  from  a 
phosphatic  guano,  this  precipitate  of  ferric  phosphate  will 
generally  be  too  large  to  allow  an  accurate  volumetric 
estimation  of  phosphoric  acid,  and  a  gravimetrical  method 
should  be  followed.     (§  93,  Jl) 

2.  To  estimate  the  insoluble  phosphate,  treat  20  grms. 
of  the  substance  with  water  to  which  20  c.c.  of  nitric  acid 
(Sp.  Gr.  =  1.4)  have  been  added,  and  digest  the  mixture 
several  hours  on  the  water-bath.  If  a  sufficient  quantity 
of  acid  was  added,  the  insoluble  residue  left  after  diges- 
tion can  be  plainly  seen,  when  stirred  up,  to  consist  of 
nothing  but  heavy  sand  and  particles  of  coal;  if  the  so- 
lution appears  to  be  incomplete,  add  10  c.c.  more  of  the 
acid  and  heat  the  mixtuie  again  several  hours ;  finally, 
filter  the  solution  into  a  litre  flask,  and  when  the  filtrate 
is  cool,  bring  its  volume  up  to  1000  c.c. ;  determine  phos- 
phoric acid  by  the  volumetric  method  (§  115,  a)  in  50  c.c. 
of  this  solution,  using  20  c.c.  of  sodic  acetate. 

This  result  gives  the  total  amount  of  phosphoric  acid 
in  the  superphosphate,  and,  as  the  soluble  phosphate  has 
already  been  determined,  the  amount  of  insoluble  phos- 
phate is  readily  estimated. 

The  insoluble  residue  of  sand  in  this  examination  may 
le  ignited  and  weighed. 

f.  Complete  analysis* — Examine  the  aqueous  solution 
prepared  above,  if  it  is  particularly  desired  to  learn  its 
composition,  according  to  Scheme  IV.,  §  94,  taking  100  c.c. 
for  (7,  and  100  c.c.  for  h  with  previous  treatment  with 
sodic  carbonate  and  potassic  nitrate ;  also  determine  chlo- 
rine in  50  c.c.  of  the  solution,  by  precipitation  with  ar- 
gentic nitrate  (§  63). 

Or,  for  a  more  complete  analysis,  including  the  determi- 
nation of  what  is  soluble  in  acid  with  what  is  soluble  in 
water,  examine  the  nitric-acid  solution  obtained  in  e  ac- 
cording to  Scheme  IV.,  except  in  case  the  phosphate 
contains  much  organic  matter,  when  it  would  be  better  to 


§  120.     GYPSUM.  237 

analyze  a  solution  of  the  ash  obtained  in  ^,  in  nitric  acid. 
^f(/2Jhuric  acid  and  chlorine,  however,  must  always  be 
determined  in  the  nitric-acid  solution  of  the  original  sub- 
stance. 

GYPSUM. 

120.  a.  Water. — Ignite  2  grms.  of  the  finely  pulverized 
gypsum  gently. 

b.  Insoluble  matters. — Digest  2  grms.,  likewise  finely 
powdered,  witli  very  dilute  hydrochloric  acid,  as  long  as 
anything  appears  to  be  dissolved,  filter  out  the  insoluble 
sand  and  clay,  wash  well  with  hot  water,  dry,  ignite,  and 
weigli  the  insoluble  residue. 

c.  Sulphuric  acid,  ferric  oxide,  lime,  etc—Divide 
the  acid  solution  in  two  equal  parts,  and  in  one  pre- 
cipitate sulphuric  acid  with  baric  chloride  (§  59),  and 
in  the  other,  after  dilution  with  water  and  heating  with 
a  little  concentrated  nitric  acid,  precipitate  ferric  oxide 
and  alumina,  with  ammonia  in  slightest  possible  excess 
(§  51).  Filter  the  precipitate  out  quickly,  so  as  to 
avoid  the  precipitation  of  calcic  sulphate  in  the  alkaline 
solution,  wash  it  Avell,  and  then  weigh  it  after  ignition. 
Immediately  on  filtering  out  this  i^recii^itate  by  ammonia, 
add  ammonic  oxalate  in  excess  to  the  filtrate  to  pre- 
cipitate the  lime  (§  49,  a),  and  estimate  magnesia  in  tlie 
filtrate  from  the  lime,  in  the  usual  way  with  hydric 
disodic  phosphate  (§  50,  b) 

d.  If  there  is  a  considerable  precipitation  of  ferric  oxide 
by  ammonia,  some  calcic  sulphate  is  very  liable  to  be 
mixed  with  it.  In  this  case,  it  is  better  to  boil  about 
1.5  grms.  of  the  finely  powdered  gypsum  an  hour  with  a 
solution  of  6-8  grms.  of  pure  sodic  carbonate ;  by  this 
operation,  if  the  gypsum  was  properly  pulverized,  it  is 
completely  converted  into  calcic  carbonate.  Filter,  wash 
the  contents  of  the  filter  well  with  liot  water,  and  precipi- 


238  §    121.       FEKTILIZEES. 

tate  the  sulphuric  acid  in  the  filtrate  with  baric  chloride ; 
transfer  the  filter  with  its  contents  to  a  deep  beaker,  and 
dissolve  the  carbonate  in  dilute  hydrochloric  acid  with 
the  usual  precautions,  filter,  wash  well,  dry,  ignite,  and 
weigh  the  i-esidue  of  sand  and  clay.  Determine  lime  and 
magnesia  in  the  filtrate  in  the  usual  manner  (§  50,  b). 

e.  Alkalies* — To  determine  these  in  gypsum,  boil  10 
grms.  repeatedly  with  dilute  hydrochloric  acid,  filter,  and 
eliminate  the  alkalies  as  chlorides  (§  93,  G.). 

f.  A  determination  of  ccirbotuG  acid  will  furnish  means 
of  estimating  the  amount  of  calcic  carbonate  in  the  gyp- 
sum ;  take  5-10  grms.  for  the  analysis  (§  60). 

SALT.     POTASH  COMPOUNDS. 

121.  A.  Salt.  a.  Water. — Gently  ignite  3-4  grms., 
well  pulverized,  in  a  platinum  crucible  that  is  kept  well 
covered,  and  carry  the  temperature  finally  to  a  dull  red. 

b.  Complete  analysis. — Dissolve  10  grms.  in  hot  water, 
filter  the  solution  into  a  litre  flask,  and  wash,  dry,  ignite, 
and  weigh  the  insoluble  residue. 

This  residue  consists  mostly  of  sand  and  clay.  If  gyp- 
sum is  contained  in  it,  digest  it  with  dilute  hydrochloric 
acid  as  long  as  anything  appears  to  be  dissolved,  filter 
the  solution,  add  ammonia  in  excess  to  the  filtrate,  filter 
out  the  precipitated  ferric  oxide  and  alumina,  precipitate 
lime  in  the  filtrate  by  ammonic  oxalate,  and  sulphuric  acid 
in  the  filtrate  from  the  calcic  oxalate  by  baric  chloride 
after  acidification  with  hydrochloric  acid. 

Bring  the  volume  of  the  aqueous  solution  of  the  salt,  ob- 
tained above,  to  1000  c.c,  and  determine  lime  and  mag- 
nesia in  400  c.c.  (§  50,  b),  and  chlorine  in  another  portion 
by  the  volumetric  process  (§  G3,  b).  Dilute  300  c.c.  with 
more  water,  acidify  it  with  hydrochloric  acid,  and  exam- 
ine the  solution  for  sulphuric  acid  and  the  alkalies  (§  93, 


§    122.       CHILI    SALTPETRE.  239 

E  and  G).     The  determination  of  potassa  in  common 
salt  is  generally  unnecessary. 

B.  Potassa  salts. — Dissolve  10  grms.  in  hot  water,  and 
determine  joo^«ss«  at  once  with  platinic  chloride  in  a  por- 
tion of  the  solution  (§  93,  G,  3). 

For  the  complete  analysis,  or  the  determination  of 
water,  proceed  as  directed  for  the  analysis  of  salt. 

CHILI  SALTPETRE. 

122.  a.  Water.— Desiccate  3  grms.  at  110°  C. 

b.  Complete  analysis. — Treat  20  grms.  of  the  pulver- 
ized salt  with  hot  water,  filter  the  solution  into  a  litre 
flask,  collect  the  insoluble  residue  on  a  dried  and  weighed 
filter,  wash  it  well  with  hot  water,  dry  it  at  125°  C, 
weigh  it,  and  then  ignite  it  at  a  low  temperature,  and 
weigh  the  ash.  These  results  give  the  amount  of  insoln- 
hle  sand  and  clay,  and,  approximately,  the  organic  tnatter. 

Bring  the  volume  of  the  aqueous  solution  to  1000  c.c, 
determine  sulphuric  acid  and  chlorine  in  two  portions  of 
200  c.c.  each,  by  precipitation  with  baric  chloride  (§  59) 
and  argentic  nitrate  (§  63),  and  lime  and  magnesia  in  an- 
other portion  of  500  c.c.  (§  50,  V), 

c.  Soda. — This  may  be  estimated  by  the  difierence 
between  the  total  amount  of  substance  taken,  and  the 
sum  of  the  acids,  water,  organic  matter,  and  the  other 
bases ;  or  it  may  be  estimated  by  converting  all  the  bases 
into  sulphates,  in  the  manner  described  for  converting 
potassa  into  sul|)hatc  (§  44),  and  weighing  the  mixture 
of  the  salts ;  then  subtract  from  this  the  sum  of  the 
weights  of  calcic  and  magnesic  sulpliate,  as  estimated  from 
tlie  determination  of  those  bases,  already  made,  and  the 
remainder  will  be  the  sodic  (and  potassic)  sulphate. 

d.  To  determine  approximately  the  amount  of  potassa^ 
if  any  is  present,  dissolve  this  residue  of  mixed  sulphates 


240  §    122.       FERTILIZERS. 

ill  very  dilute  hydrochloric  acid,  determine  sulphuric  acid 
in  the  solution  by  precipitation  with  baric  chloride  (§  59), 
deduct  so  much  of  the  sulpbuiic  acid  as  is  estimated  to 
have  been  combined  with  the  lime  and  magnesia,  and  de- 
duct also  the  corresponding  quantity  of  sulphates  from 
the  total  amount  of  sulpliates,  and  with  these  remainders 
estimate  the  potassa  and  soda  by  the  formula  for  the  in- 
direct determination  of  these  bases  (§  48,  e). 

e.  Nitric  acid. — This  may  be  determined  by  Schluss- 
ing's  process  in  10-20  c.c.  of  the  aqueous  solution  ob- 
tained in  b,  or  by  fusion  of  about  2  grms.  of  the  salt  with 
silicic  acid  (§  62).  This  estimation  can  be  dispensed 
with,  since  the  weight  of  the  nitrates  equals  the  difference 
between  the.  total  amount  of  salt  taken,  and  the  sum  of 
the  sulphates  and  chlorides,  as  already  determined. 

f.  If  the  Chili  saltpetre  is  adulterated  with  salt,  its  so- 
lution will  give  an  abundant  precipitate  with  argentic 
nitrate ;  if  adulterated  with  soda  (sodic  carbonate)  it  will 
2:ive  the  reaction  for  carbonic  acid  ;  if  with  magnesic  sul- 
phate (Epsom  salts),  it  will  give  a  decided  reaction  for 
sulphuric  acid  and  for  magnesia ;  and  if  with  sodic  sul- 
phate (Glauber's  salt),  it  will  give  a  decided  reaction  for 
sulphuric  acid,  but  none  for  magnesia. 


§    123.       ASHES    OF    PLANTS.  241 

CHAPTER    YII. 

ANALYSIS    OF    ASHES. 

I. 

ASHES  OF  PLANTS. 

123.  To  prepare  the  plant  for  incineration,  it  must  first 
be  most  carefully  cleaned  ;  and  too  much  care  cannot  be 
taken  in  this  respect,  for  if  any  particles  of  sand  or  clay 
are  left  adhering  to  the  object,  the  accuracy  of  the  analy- 
sis is  of  course  thereby  greatly  impaired,  or  the  analysis 
itself  is  rendered  much  more  difficult  of  execution. 

a.  Roots  and  tubers  must  be  cleaned  with  a  soft  brush, 
under  a  current  of  water,  and  be  afterwards  repeatedly 
rinsed  off  with  distilled  water,  and  immediately  dried 
with  a  soft  cloth.  The  dust  is  removed  from  stems  and 
leaves,  when  possible,  by  wiping  them  with  a  soft  cloth. 
/Seeds,  particularly  the  larger  kinds,  may  be  put  in  dis- 
tilled water  for  a  few  minutes,  and  immediately,  before 
the  water  can  have  time  to  penetrate  them,  put  on  a 
sieve  to  drain,  laid  on  filter  paper  and  dried  as  quickly 
as  possible  between  soft  cloths. 

b.  To  dry  the  green  parts  of  plants  and  fleshy  roots, 
hang  them  on  threads  in  a  drying-chamber,  the  roots 
being  cut  in  thin  slices.  Tubers  may  be  dried  in  the  same 
way.  Koots  and  tubers  so  dried  are  then  coarsely  pul- 
verized in  the  mortar,  while  leaves  and  stems  are  cut  up 
with  clean  shears  ;  seeds  are  broken  up  to  a  coarse  powder 
in  a  mortar. 

c.  The  incineration  is  best  efiected  in  shallow  platinum 
trays,  that  are  heated  over  the  gas-lamp,  or  in  large  cast- 
iron  muffles,  about  50  cm.  long  and  13  cm.  wide,  bujlt 

11 


242  §    123.       ANALYSIS    OF    ASHES. 

into  an  appropriate  furnace  in  such  a  manner  as  to  be 
heated  mostly  at  the  sides  and  on  the  top.  The  heat 
must,  at  first,  be  kept  very  low  for  several  hours,  or  even 
days,  while  the  substance  is  slowly  charred ;  the  coal, 
when  so  slowly  formed,  takes  a  more  porous  consistency. 
When  the  evolution  of  gases  has  nearly  ceased,  the  heat 
may  be  gradually  raised,  but  not  at  any  time  to  a  percep- 
tible red ;  in  this  way,  at  least  in  the  incineration  of  most 
of  the  fodder-plants,  roots,  and  woods,  that  yield  an  ash 
rich  in  carbonates,  a  perfect  combustion  is  obtained  with- 
out fusing  the  ash.  In  case  some  coal  remains,  that  re- 
sists combustion  without  applying  too  high  a  heat,  exhaust 
it  with  hot  water  two  or  three  times  ;  the  washed  residue 
is  usually  very  easily  burned.  Then  either  add  the  aque- 
ous solution  just  obtained  to  the  ash,  evaporate  the  mix- 
ture to  dryness  on  the  water-bath,  ignite  the  residue  very 
gently,  and  weigh  it ;  or  weigh  the  last  ash,  and  bring 
the  aqueous  extract  of  the  coal  to  a  certain  volume,  and 
for  each  part  of  the  subsequent  analysis,  mix  together 
equal  fractional  parts  of  ash  and  extract. 

Substances  rich  in  silica,  as  the  grasses,  and  the  stems 
and  chaff  of  cereals,  and  also  seeds  rich  in  alkaline  phos- 
phates, are  with  difficulty  made  to  yield  an  ash  that  is  free 
from  coal.  Such  substances  should  first  be  charred  at  a 
very  low  temperature  ;  then,  without  disturbing  the  coal 
in  tlie  dish,  moisten  it  with  a  cold  saturated  solution  of 
baric  hydrate,  dry  the  moistened  mass,  and  ignite  it  in  the 
mufile  at  a  barely  visible  red  heat ;  the  completion  of  the 
incineration  generally  requires  from  8  to  12  hours.  Enough 
baryta  water  must  be  added,  by  moistening  and  drying 
the  coal  several  times,  so  that  the  ash  will  contain  about 
half  its  weight  of  baryta.  The  addition  of  this  substance 
almost  entirely  prevents  the  escape  of  the  chlorine,  effects 
a  more  speedy  combustion  of  the  coal,  makes  the  silicates 
decomposable  by  acids,  and  insures  the  presence  of  phos- 
phoric acid  in  the  ash  in  a  readily  determinable  form. 


§  124.     ASH  RICH  IX  CARBONATES,  POOR  IX  SILICA.    243 

The  whole  quantity  of  the  ash,  in  whatever  way  ob- 
tained, should  be  most  carefully  pulverized  and  mixed 
together  before  any  sample  is  taken  for  analysis. 


A.    ASH  RICH  IN  CARBONATES,  AND  POOR  IN  SILICA. 

124.  a.  Carbonic  acid. — Determine  this  in  1-2  grms., 
using  nitric  acid  to  expel  the  carbonic  acid. 

h.  Chlorine. — Estimate  this  in  the  nitric-acid  solution 
obtained  in  a,  after  filtering  out  the  insoluble  portion. 

c.  Silica,  sand,  and  coal. — Moisten  a  portion  (3-4  grms.) 
in  a  flask,  with  concentrated  nitric  acid,  add  concentrated 
hydrochloric  acid,  and  digest  the  mixture  for  a  long  time 
at  an  almost  boiling  heat.  Rinse  the  whole  into  an  evapo- 
rating ciish,  evaporate  to  dryness,  moisten  the  residue  with 
hydrochloric  acid,  and  proceed  to  eliminate  and  deter- 
mine silica,  sand,  and  coal,  as  directed  in  §  58,  «,  3. 

If  the  ash  contains  no  sandy  particles,  as  may  be  shown 
by  the  absence  of  any  grittiness  when  the  residue,  insolu- 
ble in  hydrochloric  acid,  is  stirred  with  the  glass  rod,  the 
boiling  with  sodic  carbonate  may  be  omitted,  and  nothing 
need  be  done  but  collect  the  silica  on  a  weighed  filter,  dry 
it  at  110°,  weigh  it,  and  ignite,  and  weigh  it  again,  to 
determine  the  un consumed  carbon  that  may  be  mixed 
with  it. 

If  there  are  more  than  a  few  centigrammes  of  this  carbon 
in  three  or  four  grammes  of  the  ash,  the  substance  has  not 
been  properly  incinerated,  and  very  unreliable  results 
may  be  obtained  in  the  analysis,  particularly  as  regards 
the  phosphates  and  the  alkalies. 

d.  Complete  analysis. — Bring  the  filtrate  from  the  in- 
soluble portion  to  a  volume  of  500  c.c,  and  examine  it 
according  to  Scheme  IV.,  §  94.  If  more  than  traces  of 
manganic  oxide  are  present,  and  it  is  desired  to  estimate 
this  base,  proceed  according  to  Scheme  III.,  §  94. 


244  §    124.      ANALYSIS   OF   ASHES. 


B.    ASH  RICH  IN  SILICA,  MIXED  WITH  BARYTA. 

a.  Determine  carbonic  acid  and  clilorine,  and  pre- 
pare the  solution  for  the  complete  analysis,  precisely  as 
under  A. 

The  residue,  insoluble  in  hydrochloric  acid,  on  eliminat- 
ing silica  in  the  usual  way,  contains,  besides  sand  and 
unconsumed  carbon,  baric  sulphate,  in  which  is  the  sul; 
phuric  acid  of  the  ash,  and  it  must  be  treated  accord- 
ingly. Collect  it  on  a  dried  and  weighed  filter,  wash  it, 
dry  it  at  110°  C,  and  weigh.  Then  treat  it  with  sodio 
carbonate  (§  58,  a,  2) ;  but,  as  the  baric  sulphate  is  not 
readily  decomposed  by  the  carbonated  alkali,  the  boiling 
must  be  repeated  several  times,  with  fresh  portions  of  the 
carbonate,  the  insoluble  part  allowed  to  settle  completely 
after  each  boiling,  and  the  clear  liquid  decanted  without 
transferring  any  notable  quantity  of  the  solid  to  the  filter ; 
when  the  filtered  liquid  gives  no  reaction  for  sulphuric 
acid,  after  acidification  with  hydrochloric  acid,  the  decom- 
position may  be  considered  as  ended ;  if  the  portion  with 
which  the  test  is  made  gives  a  reaction  with  baric  chlo- 
ride, it  should  be  put  back  into  the  liquid  to  be  boiled. 

Transfer  the  silica  and  coal  to  the  filter,  after  the  boil- 
ing is  finished,  pour  dilute  hydrochloric  acid  over  it  as 
long  as  there  is  any  effervescence,  wash  the  filter  care- 
fully with  water,  dry  at  110°,  weigh,  ignite,  and  weigh 
again,  and  so  estimate  sand  and  unconsumed  carbon,  as 
under  A. 

Evaporate  the  alkaline  solutions  and  washings  to  dry- 
ness, and  eliminate  silica  (§  58),  and  determine  sulphuric 
acid  in  the  filtrate  from  the  silica,  with  the  aid  of  baric 
chloride  (§  59). 

b.  Complete  analysis* — Examine  the  solution  obtained 
in  a,  and  filtered  from  the  silica,  etc.,  according  to  Scheme 


§    124.       MISCELLANEOUS    DETERMINATIONS.  245 

III.  or  lY.,  §  94,  with  these  exceptions,  that  sulphuric  acid 
need  not  be  determined  under  a,  and  that,  before  precipi- 
tating lime  by  ammonic  oxalate,  the  barium  should  be 
removed  by  precipitation  with  a  very  dilute  sulphuric 
acid,  containing  but  one  part  of  acid  in  300-400  of  water ; 
the  precipitated  baric  sulphate  should  be  examined  for 
lime  by  heating  the  moist  precipitate  with  ammonic  car- 
bonate, washing  it,  and  then  treating  it  with  dilute  hydro- 
chloric acid,  neutralizing  the  acid  with  ammonia,  and 
adding  ammonic  oxalate. 

C.    MISCELLANEOUS  DETERMINATIONS. 

a.  Sulphur. — A  part  of  this  is  volatilized  during  the 
process  of  incineration.  In  order,  therefore,  to  determine 
the  total  amount  in  the  plant,  treat  4-5  grms.  of  the  dry 
substance  with  fused  potassic  hydrate  and  nitrate  (§  92). 

b.  Sulphuric  acid,  already  formed  in  the  plant. — A 

few  cultivated  plants  contain  more  than  mere  traces  of 
this  acid.  To  determine  it,  and  also  the  chlorine^  if  it  is 
desired,  prepare  an  extract  of  the  plant  by  water  contain- 
ing ^  I20  of  nitric  acid. 

Draw  out  one  end  of  a  glass  tube,  about  60  cm.  long 
and  1-1'  I2  cm.  in  diameter,  in  such  a  manner  that  a  rubber 
tube  and  clamp  can  be  attached,  after  the  fashion  of  a 
Mohr's  burette.  Close  the  throat  of  the  tube,  where  it 
begins  to  taper  into  the  smaller  tube,  with  a  plug  of  cot- 
ton that  has  been  previously  boiled  in  the  acidulated 
water,  such  as  is  to  be  used  for  the  extraction.  Put  8-10 
grms.  of  the  dried  substance  in  the  tube,  fill  the  latter 
with  the  acidified  water,  and  let  the  two  remain  in  contact 
several  hours ;  then  open  the  clamp,  let  some  of  the  water 
run  off,  add  fresh  acidified  water,  and  repeat  the  operation 
until  the  extract  gives  at  the  most  the  merest  opalescence 
with  argentic  nitrate. 


246  §    125.      ANALYSIS    OF   ASHES. 

In  this  acid  solution  precipitate  sulphuric  acid  with  baric 
acetate,  and  chlorine  with  argentic  nitrate  in  the  filtrate 
from  the  baric  sulphate  ;  treat  this  last  precipitate  as  one 
produced  in  the  presence  of  organic  matter,  if  it  is  at  all 
abundant. 

125.  The  following  method  of  incineration  and  analysis 
is  given  by  Reichhardt,  by  which  the  volatilization  of  any 
mineral  matters  is  avoided,  as  well  as  the  addition  of  any- 
thing to  the  ash  to  facilitate  incineration. 

1.  Carefully  char  enough  of  the  dried  substance  to  yield 
2  grms.  of  ash,  pulverize  the  coal,  and  exhaust  it  with 
several  portions  of  hot  water. 

a.  Add  argentic  nitrate  to  this  extract  immediately. 

h.  Exhaust  the  coal  with  w^ater  containing  a  little  nitric 
acid,  wash  with  the  same,  and  add  this  extract  to  a. 

2.  Incinerate  the  coal  completely,  and  exhaust  the  ash, 
first  with  water,  and  then  with  moderately  concentrated 
nitric  acid,  and  add  these  extracts  to  those  obtained  in  1. 

3.  Determination  of  sulphur  and  chlorine. — The  pre- 
cipitate by  argentic  nitrate,  in  these  extracts,  contains  the 
sulphur  that  was  present  in  a  soluble  form  in  the  plant, 
and  the  chlorine.  Acidify  the  mixture  of  precipitate  and 
liquid  with  nitric  acid,  if  not  already  acid,  collect  the 
precipitate  of  argentic  sulphide  and  chloride  on  a  dried  and 
weighed  filter,  wash  it  well,  and  add  the  filtrate  and  wash- 
ings to  those  obtained  in  4,  below.' 

Treat  the  precipitate  on  the  filter  with  ammonia,  by 
w^hich  the  argentic  chloride  is  dissolved,  wash  the  insolu- 
ble argentic  sulphide,  dry  it  at  100°,  and  weigh.  It  con- 
tains 12. 9° 1 0  of  sulphur. 

Precipitate  argentic  chloride  in  the  ammonio  extract,  by 
nitric  acid  in  excess,  and  treat  the  precipitate  in  the  usual 
manner  (§  63). 

4.  Heat  the  residue,  insoluble  in  nitric  acid  in  2,  with 


§    126.       MISCELLANEOUS    DETERMINATIONS.  247 

concentrated  hydrochloric  acid,  and  filter.  By  mixing  this 
filtrate  with  that  obtained  in  3,  the  excess  of  silver  is  pre- 
cipitated, and  may  be  removed  from  the  solution  by  fil- 
tration. 

« 

5.  Treat  the  residue,  insoluble  in  hydrochloric  acid,  as 
directed  in  §  58,  a,  3,  for  the  separation  of  silica,  sand, 
and  coal. 

6,  Eliminate  the  silica  in  the  hydrochloric  solution  fil- 
tered from  the  excess  of  silver  in  4,  in  the  usual  manner 
(§  58,  a,  1),  and  examine  the  filtrate  from  the  silica  ac- 
cording to  Scheme  III.  or  lY.,  §  94,  according  to  whether 
manganese  is  or  is  not  to  be  determined. 

126.  Statement  of  results. — So  much  sodium  as  is  nec- 
essary .to  combine  with  all  the  chlorine  should  be  consid- 
ered as  so  combined,  while  the  remainder  of  the  sodium  is 
given  as  sodic  oxide. 

If  there  is  not  sodium  enough  for  this  purpose,  take 
enough  of  the  potassium  to  combine  with  what  chlorine 
is  left,  and  give  the  remainder  of  the  potassium  as  potassic 
oxide. 

The  manganese  is  to  be  given  as  manganous  manganic 
oxide,  Mn3  0,. 

The  sand  and  coal  are  accidental  ingredients  of  the  ash, 
and  therefore  the  percentage  composition  should  be  calcu- 
lated with  reference  to  what  is  left  after  subtracting  these 
from  the  weight  of  ash  taken  for  analysis. 

The  percentage  composition  should  moreover  be  given 
with  reference  to  the  remainder  left  after  subtracting  the 
carbonic  acid  also,  since  this  is  not  properly  one  of  the 
mineral  substances  found  in  the  plant,  but  results  from  the 
combustion  of  the  organic  acids. 

The  first  statement  enables  one  to  judge  of  the  accuracy 
of  the  analysis,  and  the  second  gives  the  real  composition 
of  the  mineral  matter  found  in  the  particular  plant  exam- 
ined. 


248 


121 


ANALYSIS    OF    ASHES. 


Analysis  of  the  ash  of  hops.     (Wheeler.) 


Potassa , 

Soda 

Lime 

Magnesia , 

Ferric  oxide 

Manganous  manganic  oxide 

Alumina , 

Pliosphoric  acid 

Sulpburic  acid 

Potassic  cliloride 

Sodic  chloride 

Silicic  acid , 

Carbonic  acid 

Charcoal  and  sand 

Total  ash 


CO2,  coal, 

etc., 

CO2,  etc., 

included. 

deducted. 

37.79 

44.33 

11.36 

13.33 

1.27 

1.49 

0.48 

0.56 

trace. 

trace. 

12.67 

14.86 

1.98 

2.32 

8.48 

9.94 

1.21 

1.41 

10.03 

11.76 

12.50 

1.91 

99.67 

100.00 

9.14 

II. 


THE  ASH  OF  ANIMAL  SUBSTANCES. 


127 1  Animal  substances  are  incinerated  with  difficulty, 
particularly  when  they  fuse  before  they  become  charred; 
the  attempt  should  be  made,  however,  to  burn  them  with- 
out the  addition  of  any  agents. 

First  char  the  dry  substance  in  a  platinum  dish,  raising 
the  heat  very  slowly,  so  as  to  avoid  fusion,  if  possible ; 
when  the  charring  has  attained  such  a  point  that  water  is 
no  longer  colored  when  left  for  a  time  in  contact  with  the 
coal,  break  the  coal  up  into  a  coarse  powder,  and  boil  and 
wash  it  several  times  with  water,  acidified  with  a  little 
nitric  acid  in  case  no  carbonates  are  present,  or  carbonic 
acid  is  not  to  be  determined  ;  then  dry  tlie  coaly  residue 
and  complete  the  incineration  in  the  muffle,  at  a  barely 
visible  red  heat. 

Sometimes  it  will  be  found  necessary  to  repeat  the 
exhaustion  with  water  and  heating  in  tlie  muffle  several 
times,  before  the  incineration  can  be  completed. 


§    128.       ASHES    OF   FTTEL.  249 

This  process,  will,  however,  hardly  succeed  in  many 
cases,  and  usually  only  when  the  ash  yielded  by  the  sub- 
stance is  rich  in  alkaline  carbonates  or  sodic  chloride,  or 
when  but  a  small  quantity  of  the  substance  is  incinerated 
in  order  to  determine  the  total  amount  of  ash.  Since  a 
considerable  proportion  of  alkaline  phosphates  is  often 
present,  which  is  converted  into  pyrophosphate  during 
the  incineration,  it  is  generally  necessary  to  treat  the 
charred  substance  ^^•ith  baryta  water,  in  the  manner  di- 
rected for  the  incineration  of  vegetable  substances  rich  in 
phosphates. 

In  the  analysis  of  the  ash,  proceed  as  directed  for  the 
analysis  of  ashes  of  plants,  with  the  exception  that,  since 
silicic  acid  and  sand  are  rarely  present,  the  work  is  some- 
what simplified.  The  total  sul])hur  should  be  determined 
in  a  portion  of  the  substance  that  has  been  heated  with 
potassic  hydrate  and  nitrate  (§  92). 

III. 

ASHES  OF  FUEL. 

128.  a.  Carbonic  Acid. — Determine  this  in  2  grms. 
h.  Chlorine* — Determine  this  in  the  nitric-acid  solution 
obtained  in  a. 

c.  Complete  Analysis. — Conduct  this  as  directed  for  the 
analysis  of  the  ash  of  plants  poor  in  silica.  (§  124,  c,  d.) 
The  estimation  of  potassa  and  phosj^horic  acid  is  of  most 
importance  in  respect  to  the  agricultural  value  of  the 
ashes.  10-15  grms.  of  wood  ashes,  or  15-25  gnns.  of 
peat  or  coal  ashes,  should  be  treated  with  acid,  in  order  to 
prepare  a  sufficient  quantity  of  the  solution. 

d.  Potassa. — For  a  volumetric  determination  of  potassa 
that  will  answer  very  well  for  practical  purposes,  treat 
6.91  grms.  of  the  wood  ashes  in  a  flask  of  about  300  c.c. 
capacity  with  5-6  grms.  of  caustic  lime  and  40-60  c.c.  of 

11* 


250  §    128.       ANALYSTS    OF    ASHES. 

water,  and  heat  the  mixture  to  boiling.  Filter  the  solu- 
tion into  a  graduated  cylinder,  and  wash  the  insoluble 
residue  with  sufficient  water  to  make  the  volume  of  the 
solution  exactly  100  c.c,  when  properly  cooled.  Titrate 
10  c.c.  of  this  solution  with  the  normal  acid  (§  44,/*), 
subtract  0.3  c.c.  for  the  excess  of  lime,  and  then  multiply 
the  number  of  cubic  centimetres  required  by  10,  for  the 
per  cent  of  potassic  carbonate. 

Peat  and  Coal  Ashes  are  usually  very  poor  in  alkalies 
and  phosphoric  acid.  Their  agricultural  value  depends 
more  particularly  on.  the  amount  of  calcic  sulphate 
(gypsum),  and  calcic  carbonate  and  phosphate,  which  they 
contain. 

Many  kinds  of  peat  leave  ashes  that  are  rich  in  gypsum ; 
in  such  cases  it  is  well  to  boil  about  2  grms.  of  the  ashes 
an  hour,  with  a  solution  of  6-8  grms.  of  sodic  carbonate, 
and  determine  sulphuric  acid  in  the  aqueous  solution  so 
obtained,  and  lime  in  the  hydrochloric  solution  of  the 
residue  insoluble  in  water. 


§    129.      FODDER.  251 

CHAPTER    VIII. 

FODDER    AND    FOOD. 

I 

FODDER. 

129.  In  the  examination  of  fodder,  it  is  very  desirable 
that  chemists  should  follow  a  common  method. 

The  processes  of  analysis  that  have  been  perfected  at 
the  experimental  station,  Weende,  by  Henneberg,  Stoh- 
mann,  Rautenberg,  Kiihn,  Aronstein,  and  Schulze,  com- 
mend themselves  for  general  use. 

a.  Preparation  of  the  Sample  for  Analysis.— In  order 
that  the  sample  may  fairly  represent  a  large  quantity  of 
the  fodder,  a  handful  should  be  taken  here  and  there  from 
all  parts  of  the  pile  or  the  field,  till  15-20  such  portions 
are  obtained:  mix  the  whole  well  together,  and  take 
about  1  kilo,  of  dry  fodder  or  3-4  kilos,  of  green  for  the 
sample. 

Cut  it  up  with  shears,  weigh  it,  dry  it  for  several  days 
in  a  drying-chamber  at  50-60°,  expose  it  to  the  air  24 
hours,  and  weigh  it  again  in  this  air-dried  condition. 

b.  Hygroscopic  Water, — Grind  50  to  100  grms.  of  the 
dry  substance  quickly  in  a  steel  mill  and  desiccate  10  grms. 
of  this  powder  at  110°  C. 

c.  IVon-TOlatile  Matter. — Incinerate  the  dried  sub- 
stance obtained  in  b,  subtract  carbonic  acid  and  coal,  and 
calculate  the  non-volatile  matter  in  the  fodder  as  it  was 
taken  for  analysis, 

130.  Reduce  the  rest  of  the  air-dried  substance  to  a 
fine  powder,  by  alternate  grinding  and  sifting,  and  pre- 
serve it  in  well-stoppered  bottles. 

a.  Water. — Desiccate  3-5  grms.   of  this    powder    at 


252  §    130.       FODDER   AND   FOOD. 

110°  C.,and  calculate  the  amount  of  dry  substance  in  the 
powder. 

h.  Protein  Compounds. — ^Ignite  0.7  to  1  grm.  with 
soda-lime  (§  85). 

c.  Fatty  Substances. — Extract  these  from  6-8  grms., 
by  ether  (§  87). 

d.  Crude  Cellulose.— Boil  a  quantity  of  the  powder 
containing  about  3  grms.  of  dry  substance,  half  an  hour, 
with  200  c.c.  of  dilute  sulphuric  acid,  containing  1.25°  |„ 
of  monohydrated  acid,  in  a  flask  that  is  attached  to  the 
lower  end  of  a  Liebig's  condenser;  let  the  mixture  stand 
till  the  solid  particles  settle  to  the  bottom ;  draw  the  clear 
liquid  off  into  a  beaker,  as  completely  as  possible,  with  a 
small  siphon,  and  finally  with  a  pipette  ;  pour  200  c.c. 
of  water  over  the  residue  in  the  flask,  boil  again  half  an 
hour  in  the  same  manner  as  before,  and  as  before  let  the 
solid  particles  settle  and  remove  the  clear  liquid ;  repeat 
this  operation  once  more. 

Then  boil  the  substance  in  the  same  way  with  150  c.c. 
of  water  and  50  c.c.  of  a  solution  containing  50  grms.  of 
fused  caustic  potash  in  the  litre,  and  afterwards  twice  with 
200  c.c.  of  water,  removing  the  liquid  each  time  in  the 
same  manner  as  described  for  the  sulphuric  acid,  but  put- 
ting these  alkaline  washings  in  a  beaker  bj^  themselves ; 
finally,  bring  the  residue  on  a  dried  and  weighed  filter. 
Then,  with  the  siphon,  draw  off"  the  clear  alkaline  liquid 
from  any  sediment  that  may  have  been  deposited  in  it ; 
transfer  this  sediment  to  the  same  filter,  and  wash  the 
whole,  as  long  as  the  Avashings  have  an  alkaline  reaction ; 
then  add  the  sediment  in  the  beaker  containing  the  acid 
washings,  after  drawing  ofi*  the  clear  liquid  with  the 
siphon,  and  wash  again,  as  long  as  the  washings  have  an 
acid  reaction.  Wash  the  contents  of  the  filter  succes- 
sively with  alcohol  and  ether ;  dry  the  filter  and  its  con- 
tents at  110°,  weigh,  incinerate  the  residue,  and  weigh 


§    131.       FODDER.  253 

the  ash.  The  difference  between  the  total  weight  of  the 
insoluble  residue  and  that  of  the  ash  equals  the  crude 
cellulose  or  fibre. 

The  residue  obtained  in  this  way  is  a  mixture  of  cellu- 
lose with  various  other  substances.  When  obtained  from 
the  grasses  it  is  comparatively  the  purest,  but  contains 
2-3"!  g  of  protein  compounds.  When  prepared  from  clover, 
it  contains  5-6"  \^  of  the  same  substances  ;  but  even  after 
subtraction  of  these  albuminoids,  the  residue  contains 
1-7°  lo  more  carbon  than  pure  cellulose. 

131.  a.  Dry  Matter  Soluble  in  Water.— To  determine 
the  amount  of  substance  soluble  in  water,  boil  10-20 
grms.  with  10-12  successive  portions  of  200-300  c.c.  of 
water  in  a  flask  that  is  connected  with  the  lower  end  of  a 
Liebig's  condenser  (§  39,  <?),  and  after  each  boiling,  sepa- 
rate the  water  as  quickly  as  possible  from  the  residue ;  all 
the  portions  of  w^ater  are  afterwards  passed  through  a 
ribbed  filter,  that  is  j)ierced  with  the  glass  rod  and 
replaced  by  a  new  one  as  often  as  it  becomes  choked  up, 
so  that  the  filtration  shall  proceed  as  rapidly  as  possible. 
Bunsen's  method  of  filtration  can  be  used  in  this  case  to 
great  advantage. 

The  extraction  should,  at  any  rate,  be  finished  in  one 
day,  so  that  the  solution  may  not  begin  to  mould  before 
it  is  examined. 

Evaporate  200  c.c.  of  the  extract  almost  to  dryness,  in 
a  platinum  dish,  on  the  water-bath  ;  complete  the  desic- 
cation on  hot  sand,  under  the  receiver  of  the  air-pump 
(§  90),  and  weigh  the  residue. 

b.  IVon-Tolatile  Matter  Soluble  in  Water.— Incinerate 
the  residue  obtained  in  a.  Generally  an  ash  free  from 
coal  can  be  obtained ;  if  not,  filter  out  and  weigh  the 
coal  in  the  usual  manner,  and  subtract  it  and  the  carbonic 
acid  from  the  total  residue. 

An  excess  of  mineral  matters  is  always  found  in  this 


254  §    131.       FODDER   AND   FOOD. 

solution,  for  the  water  dissolves  some  of  the  glass  with 
which  it  comes  in  contact. 

If  it  is  not  desired  to  subject  the  residue  insoluble  in 
water  to  further  treatment  with  alcohol  and  ether,  as 
below,  it  can  be  dried  and  weighed,  and  ash  and  nitrogen 
determinations  made  with  portions  of  it ;  then,  by  sub- 
tracting the  amount  of  ash  and  nitrogen  found  in  it  from 
what  was  found  in  the  original  substance,  the  amount  that 
should  be  found  in  the  aqueous  extract  may  be  estimated, 
and  thus  the  tedious  evaporation  of  a  portion  of  that ' 
extract  to  dryness  be  avoided;  or  the  two  sets  of  deter- 
minations may  be  made  to  control  each  other  ;  the  differ- 
ence between  the  amount  of  substance  taken  for  extraction 
with  water  and  the  weight  of  the  insoluble  substance, 
above  determined,  will  give  the  amount  soluble  in  water. 

Or,  since  the  alcohol  and  ether  used  for  extracting  the 
residue  insoluble  in  water,  as  below,  usually  take  up  but 
traces  of  mineral  matters,  we  can,  in  case  these  solvents 
take  but  a  few  per  cent  of  that  residue  into  solution, 
consider  the  residue  insoluble  in  alcohol  and  ether  as  con- 
taining the  same  amount  of  ash  ingredients  as  the  residue 
insoluble  in  water  only,  and  the  determination  of  the 
ash  in  this  will  answer  the  same  purpose  as  if  estimated 
in  the  first  insoluble  residue. 

c.  Nitrogen  in  Forms  Soluble  in  Water.— Evaporate 
500-1000  c.c.  of  the  aqueous  extract  to  a  syrup,  on  the 
water-bath,  absorb  the  residue  by  as  small  a  quantity  of 
calcined  gypsum  as  possible,  collect  the  whole  in  a  watch- 
glass,  dry  it  for  a  while  at  88-90°  C,  and  ignite  the  residue 
with  soda-lime  (§  85,  a). 

d.  Actual  Ammonia. — Detennine  this  in  a  portion  of 
the  aqueous  extract,  by  Schlossing's  method.  Acidify 
300  c.c.  of  the  extract  with  hydrochloric  acid,  and  con- 
centrate it.  A  more  accurate  result  may  be  obtained  by 
Knop's  method  of  setting  free  the  nitrogen  and  measuring 


§    131.       FODDEK.  255 

its  volume  in  the  azotometer.     [See  Fresenius's    Quan- 
titative A^ialysis.) 

e.  Sugar  and  Gum  in  Aqueous  Extract.— Evaporate 
500  to  1000  c.c.  nearly  to  dryness,  as  quickly  as  it  can  be 
done  without  loss,  and,  if  j^ossible,  in  a  space  where  the 
air  can  be  rarefied,  and  exhaust  the  moist  residue  with 
alcohol  of  80-85"  Iq,  by  repeated  boiling  with  fresh  por- 
tions of  the  solvent,  as  long  as  it  is  colored.  Filter  the 
liquid,  add  water  to  the  filtrate,  expel  the  alcohol  by  heat, 
filter  through  animal  charcoal,  if  necessary,  bring  this 
filtrate  to  a  certain  volume,  and  estimate  glucose  and 
saccharose  (§  81). 

Dry  the  residue  insoluble  in  alcohol  at  100°  C,  weigh, 
and  incinerate  it.  Subtract  the  ash  and  protein  com- 
pounds, as  may  be  estimated  from  determinations  already 
made,  from  the  total  amount  of  the  residue  insoluble  in 
alcohol,  and  call  the  remainder  gum  and  vegetable  acids. 

f.  Nitric  Acid. — To  control  the  determination  of  nitro- 
gen already  made  in  a  portion  of  the  aqueous  extract, 
nitric  acid  maybe  determined,  in  addition  to  the  ammonia 
already  estimated;  thus  it  may  be  leanied  how  much 
of  the  nitrogen  is  present  in  the  form  of  these  inorganic 
substances. 

Evaporate  500-1000  c.c.  of  the  aqueous  extract  to  a 
small  bulk,  and  determine  nitric  acid  by  Schlossing's 
method  (§  62,  a). 

Friihling  and  Grouven  {LandwirthscK  Versuchs-zSta- 
tionen,  9,  9)  prepare  the  aqueous  extract  of  the  plant, 
particularly  for  the  determination  of  nitric  acid,  as  fol- 
lows :  Put  100-500  grms.  of  the  finely  divided  but  not 
ground  air-dried  substance  in  strong  beakers  of  a  capacity 
of  two  litres;  add  enough  50"  |q  alcohol,  so  that  the  whole 
mass  of  the  solid  will  be  completely  covered,  when  pressed 
down  firmly  with  a  pestle  and  kept  down  by  a  plate 
w^eighted  with  a  glass  filled  with  mercury. 


266  §    132.       FODDEK    AND    FOOD. 

After  12  hours,  pour  off  the  dark-colored  liquid,  wrap 
the  solid  mass  in  a  linen  bag,  and,  with  a  powerful  screw- 
press,  force  out  the  remainder  of  the  alcohol.  Pour 
diluted  alcohol  over  the  press-cake  4  or  5  times,  and  each 
time  press  the  liquid  out  completely.  In  this  way  1-2 
litres  of  a  highly-colored  alcoholic  extract  are  obtained. 
Heat  the  liquid  almost  to  boiling  till  all  the  alcohol  is 
volatilized,  evaporate  it  to  a  small  bulk,  add  an  excess  of 
rather  thick  milk  of  lime,  and  boil  the  mixture  for  some 
time  ;  allow  the  precipitate  to  subside,  draw  off  the  clear 
liquid  with  a  siphon,  filter  the  remainder  through  linen, 
and  wash  the  residue  well ;  heat  the  solution  thus  ob- 
tained, pass  carbonic  acid  through  it,  boil  and  filter; 
evaporate  the  filtrate  to  a  small  bulk,  and  use  the  whole 
of  it  for  the  determination  of  nitric  acid  by  Schlossing's 
process  (§  62,  a),  in  case  there  is  reason  to  believe  that  but 
little  is  present ;  or  a  part  of  it  may  be  used  for  this  pur- 
pose, and  the  remainder  treated  as  directed  above  for  the 
examination  of  the  aqueous  extract. 

132.  If  it  is  desired  to  estimate  still  more  in  detail  the 
no7i-nitroge7ious  substances  in  the  fodder,  boil  the  residue 
that  is  insoluble  in  water  (§  131,  a),  first  with  common, 
and  then  with  absolute  alcohol,  so  long  as  the  washings 
are  colored ;  then  extract  this  second  residue  with  ether ; 
these  extractions  can  be  most  conveniently  made  with  the 
aid  of  the  washing-bottle  filtering  arrangement  (§  39,  c). 

a.  Evaporate  both  the  extracts,  or  aliquot  parts  of 
them,  to  dryness,  to  determine  the  amounts  taken  into 
solution. 

h.  Crude  Cellulose.— Treat  2-4  grms.  of  the  residue 
that  has  been  exhausted  with  alcohol  and  ether  above,  as 
directed  in  §  78. 

In  case  solid  excrements  are  being  analyzed  to  deter- 
mine the  amount  of  cellulose  in  them  as  compared  with 
fodder,  a  longer  maceration  is  advisable,  for  14-16  days, 
instead  of  12-14. 


§    133.       BEETS,    TURNIPS. 


257 


c.  starch. — ^Wash  2  grms.  of  the  powdered  substance 
on  a  filter,  with  cold  water,  and  then,  if  much  gluten  is 
joresent,  wash  with  alcohol  containing  sulphuric  acid,  and 
finally  with  water.  Treat  the  residue  with  dilute  sul- 
phuric acid  or  malt,  to  convert  the  starch  into  glucose, 
and  estimate  the  glucose  with  the  standard  cupric  solution 

(§  81). 

The  difference  between  the  sum  of  the  weights  of  the 
cellulose,  protein  compounds,  and  mineral  ingredients  in 
the  dried  substance,  and  the  weight  of  the  substance 
insoluble  in  water,  alcohol,  and  ether,  gives  the  amount  of 
difficultly  soluble  non-nitrogenous  matters,  of  which  starch 
will  form  a  considerable  part. 

Analysis  of  the  Pea.     (Yoelcker.) 

Pen.        Pod.       Vine. 


W:it^- 

Ash  or  uon-volatile  matter. . . . 

Protein  compounds 

Fat 

Cellulose  (fibre) 

Starch .^. 

Su^ar r 

Other  non-nitrogenous  matter. 


14.1 

2.5 
23.4 

2.0 
10.0 
37.0 

2.0 

9. 


100.00 


13.68 
2.75 
7.12 
1.09 

53.71 


21.65 


100.00 


16.02 
4.93 
8.86 
2.34 

42.79 


25.00 


100.00 


BEETS,   TURNIPS. 


133.  To  estimate  the  value  of  tliese  for  fodder,  deter- 
minations of  water,  albuminoids,  mineral  matters,  cellu- 
lose, and  the  total  amount  of  other  non-nitrogenous 
matters,  are  important. 

For  the  manufacture  of  sugar,  the  estimation  of  this 
ingredient  is  of  greatest  importance. 

The  part  of  the  beet  that  is  insoluble  in  water  consists 
mostly  of  cellulose  and  pectose,  while  in  the  aqueous  solu- 
tion, sugar,  inorganic  salts,  and  albuminoids,  are  to  be 
found. 

a.  Water. — Slice  the  roots  after  they  have  been  proper- 


258  §    133.       FODDER   AND    POOD. 

ly  cleaned  ;  or,  if  they  are  very  large,  select  15-20  from 
the  lot,  cut  each  one  in  halves  from  top  to  bottom,  and 
take  a  thin  slice  from  the  inside  of  each  half. 

If  sugar  is  to  be  determined  for  technical  purposes,  the 
crown  and  end  of  the  root  should  be  cut  off,  in  the  man- 
ner practised  at  the  manufactory,  before  slicing  it. 

Weigh  quickly  the  whole  number  of  slices  thus  ob- 
tained, to  the  amount  of  500-1000  grms.,  and  dry  them 
on  threads  in  the  drying-chamber  at  a  tetnperature  of 
60-70°  C.  Pulverize  this  dried  substance  coarsely,  mix  it 
well  together,  and  weigh  the  whole  quantity,  determine 
hygroscopic  water  in  a  portion  of  5-6  grms.,  and  keep  the 
rest  in  well-stoppered  bottles. 

h.  Non-Tolatilc  matter,  nitrogen,  fat,  crude  cellulose. 

— ^Determine  these  as  directed  under  Fodder  (§  129,  c, 
§  130,  h,  c,  d). 

c.  Pectose  compounds. — These  are  estimated  by  the 
difference  between  the  weight  of  the  dry  substance  and 
the  sum  of  the  weights  of  the  above-named  substances  in 
h,  and  the  sugar. 

d.  Sugar. — Boil  2-3  grms.  of  the  powdered  substance 
with  several  fresh  portions  of  80-85"  |q  alcohol,  as  long  as 
anything  appears  to  be  taken  into  solution ;  pour  each 
portion  of  alcohol  through  a  filter  that  has  been  dried  at 
100°  and  weighed,  and  finally  put  the  whole  insoluble 
substance  on  the  same  filter,  wash  it  with  hot  alcohol,  dry 
it  at  100°,  and  weigh,  ignite  it,  and  weigh  the  ash.  The 
amount  of  organic  matter,  burned  off  by  the  ignition, 
can  then  be  estimated  ;  it  consists  almost  entirely  of  sugar. 

To  determine  the  sugar  more  accurately,  add  considera- 
ble water  to  the  alcoholic  solution,  heat  the  mixture  on 
the  water-bath  until  the  alcohol  is  entirely  evaporated,  di- 
lute the  residue  to  about  300  c.c,  add  5-6  c.c.  of  concen- 
trated sulphuric  acid,  heat  the  mixture  3  hours  on  the 
water-bath,  neutralize  the  free  acid  with  sodic  carbonate, 


§    133.       BEETS,    TURNIPS.  259 

and  determine  glucose  in  an  aliquot  part  of  the  solution, 
having  first  added  water,  if  necessary,  to  make  the  volume 
of  the  solution  one  that  can  be  easily  divided  into  aliquot 
parts ;  calculate  the  result  obtained  for  saccharose,  if  the 
root  examined  was  the  sugar  beet ;  in  other  roots,  and  in 
the  sap  of  plants,  glucose  is  found,  as  well  as  cane  sugar, 
and  the  determination  should  be  made  accordingly  (§  83). 

To  examine  the  root  in  its  fresh  state  for  sugar,  enclose 
a  weighed  quantity  of  the  finely  grated  root  in  a  flannel 
bag,  and  press  the  sap  out  of  it ;  weigh  the  press-cake, 
and  determine  water  in  one  portion  of  20-30  grms.  by 
desiccation  at  100° ;  on  the  basis  of  this  determination, 
the  amount  of  sugar  still  remaining  in  the  cake  can  be 
estimated,  the  solution  in  the  cake  being  of  course  of  the 
same  strength  as  that  expressed. 

Weigh  or  measure  the  sap  that  was  pressed  out,  and 
determine  sugar  in  an  aliquot  part  of  it. 

In  the  case  of  the  sugar  beet,  it  may  be  assumed  with 
tolerable  safety  that  it  contains  94"  !„  of  water,  and  we 
may  therefore  express  a  small  quantity  of  the  sap  from  a 
weighed  quantity  of  the  grated  root,  and  determine  sugar 
in  50  c.c.  of  it,  in  the  usual  manner  (§  83). 

An  approximate  estimation  of  sugar  in  beets  may  be 
made  by  determining  their  specific  gravity  according  to 
the  method  described  in  §  35,  e. 

Take  10-12  beets  from  different  parts  of  the  lot,  clean 
them  carefully,  cut  each  one  in  four  equal  sections,  across 
its  longitudinal  axis,  and  use  the  second  piece  from  the 
top  for  the  determination  of  the  specific  gravity.  The 
temperature  of  the  saline  solution  should  be  about  18°  C. 

The  relation  between  the  specific  gravity  of  the  beet 
and  the  percentage  of  sugar,  as  well  as  of  total  dry  sub- 
stance, is  given  in  Table  YI. 

When,  in  these  estimations  of  sugar  with  the  cupric  so- 
lution, the  solution  of  sugar  is  not  properly  clarified  by 
the  plumbic  acetate,  heat  a  measured  quantity  of  it  nearly 


260  §    133.       FODDER    AND    FOOD. 

to  boiling,  add  a  few  drops  of  milk  of  lime,  whereby  a 
heavy  precipitate  is  usually  produced ;  then  filter  the 
liquid  through  granular  animal  charcoal,  free  from  dust, 
and  repeat  this  filtration  until  the  solution  is  sufiiciently 
decolorized.  If  any  evaporation  of  the  water  is  avoided 
in  the  course  of  this  operation,  the  sugar  can  be  deter- 
mined at  once  in  a  measured  portion  of  the  filtrate ;  other- 
wise, the  coal  must  be  well  washed,  the  filtrate  and  wash- 
ings perfectly  mixed,  and  the  estimation  of  the  sugar,  for 
the  whole  amount  of  solution  taken  originally,  based  upon 
the  ratio  between  the  volume  of  this  solution  and  that  in 
an  aliquot  part  of  which  the  sugar  is  determined  with  the 
cupric  solution. 

e.  Ammonia* — Treat  80  c.c.  of  the  sap  with  enough 
plumbic  acetate  to  effect  complete  precipitation,  filter  the 
liquid,  and  use  20  c.c.  of  the  filtrate  for  the  determination 
by  Schlossing's  process  (§  47,  h). 

f.  Nitric  acid. — Determine  this  according  to  Schloss- 
ing's process  (§  62,  «),  in  10-20  c.c.  of  the  concentrated 
sap,  containing  not  more  than  2-2.5  grms.  of  organic  mat- 
ter ;  an  amount  of  ferrous  chloride,  containing  6-7  grms. 
of  metallic  iron,  should  be  used  for  1  grm.  of  dry  sub- 
stance in  the  quantity  of  sap  taken. 

Hugo  and  Ernst  Schulze  found  it  best  to  make  an  alco- 
holic extract  of  from  4-10  grms.  of  the  dried  and  powder- 
ed root,  according  to  its  richness  in  nitric  acid,  with  90°  |(, 
alcohol,  with  the  aid  of  heat ;  the  extract  was  evaporated 
to  dryness,  the  residue  dissolved  in  water,  and  the  solu- 
tion filtered,  if  necessary ;  nitric  acid  was  determined  in 
this  filtrate.    {Landwirthsch.  Versuchs-iStationen,  9,  447.) 

ff.  Starcll. — Some  roots,  and  particularly  carrots,  con- 
tain a  notable  quantity  of  starch.  To  estimate  it,  mash 
an  amount  of  the  root  containing  3-4  grms.  of  dry  sub- 
stance with  cold  water,  rinse  the  mixture  into  a  beaker, 
add  more  water,  stir  the  whole,  and  let  it  stand  half  an 


§    134.      POTATOES.  261 

hour;  decant  the  supernatant  liquid  on  a  dried  and 
weighed  filter,  and  finally  transfer  the  insoluble  residue  to 
the  same  filter ;  Avash  the  filter  well  with  cold  water,  re- 
move most  of  the  water  from  its  contents  by  pressure 
between  folds  of  filter-paper,  dry  the  whole  at  100°,  and 
weigh.  Treat  the  filter  and  its  contents  with  extract  of 
malt,  and  determine  glucose  in  the  product  (§  81). 

POTATOES. 

134.  Prepare  them  for  examination  as  directed  in  §  133,a. 

a.  Water. — Dry  250-500  grms.  of  the  potatoes,  and 
determine  hygroscopic  water  also,  as  directed  in  §  133,  a, 
in  the  examination  of  roots. 

h.  Dry  substance  soluble  in  water. — Cut  several  pota- 
toes very  fine,  and  crush  30  grms.  )f  the  carefully  mixed 
sample  with  cold  water,  in  a  mortar,  and  separate  the 
soluble  from  the  insoluble  part  in  the  same  manner  as  di- 
rected in  §  133,  g. 

Dry  the  insoluble  residue  at  100°  C,  weigh  it,  inciner- 
ate it  in  the  muffle  (§  123,  c),  and  weigh  the  ash  ;  thus  we 
have  determined  the  organic  and  the  inorganic  matter  in- 
soluble in  water.  The  difference  between  the  weight  of 
the  dried  insoluble  residue  and  the  amount  of  substance 
taken  gives  the  weight  of  soluble  matter  in  it. 

Bring  the  aqueous  solution  to  any  easily  divisible  vol- 
ume, and  heat  about  ^  I3  of  it  to  boiling.  Albumen  is  pre- 
cipitated, and  may  be  collected  on  a  weighed  filter,  dried 
at  100°,  and  weighed. 

Evaporate  the  filtrate  from  the  albumen  to  dryness  on 
the  water-bath,  weigh  the  residue,  ignite  it,  and  weigh  the 
ash ;  thus  organie  and  inorganic  matters,  soluble  in 
water,  are  determined. 

c.  Albuminoids. — Evaporate  another  third  of  the  solu- 
tion almost  to  dryness,  mix  the  moist  residue  with  calcined 


262  §    135.       FODDER    AND    FOOD. 

gypsum,  dry  it  at  100-105°  C,  and  ignite  the  residue 
with  soda-lime  (§  85). 

d.  Starch. — Determine  this,  together  with  a  small  quan- 
tity of  gum,  in  2.5-4  grms.  of  dry  substance  (§  79). 

For  technical  purposes,  it  is  often  sufficient  to  determine 
the  specific  gravity  of  the  potato,  in  order  to  estimate  ap- 
proximately the  goodness  of  the  tuber,  or  the  amount  of 
dry  substance  and  starch  that  it  contains. 

Determine  the  specific  gravity  as  directed  in  §  35,  e. 
The  temperature  of  the  saline  solution  should  be  about 
16°  C  The  relation  between  the  specific  gravity  and  the 
amount  of  dry  substance  and  starch  is  given  in  Table  YII. 
Potatoes  that  have  been  afifected  by  disease  cannot  be 
examined  in  this  way  unless  the  diseased  parts  are  cut  out. 

Artichokes  may  be  examined  in  the  same  way  as 
potatoes,  except  that  the  aqueous  extract  of  the  former 
should  be  more  carefully  examined  for  glucose.  The 
inulin  in  the  artichoke  is  converted  into  glucose  somewhat 
more  easily  than  the  starch  in  potatoes. 

SEEDS.    MEAL.    FLOUR. 

135.  Seeds  are  crushed  in  a  mortar  or  ground  to  a  fine 
powder  in  the  steel  mill. 

a.  Water. — Desiccate  5-10  grms.  of  the  powder,  and 
preserve  the  rest  in  well-stoppered  bottles. 

h.  Non-yolatile  matter,  protein  compounds,  fat,  crude 
cellulose. — Estimate  these  precisely  as  directed  for  the 
examination  of  fodder  (§  129,  c,  §  130,  5,  c,  d), 

c.  Dry  substance  soluble  in  water.— Determine  this 

as  directed  in  §  134,  5,  with  20  grms.  of  the  powder, 

d.  Starch. — Follow  any  of  the  methods  described  in 
§  ^9. 

Or,  wash  2  grms.  of  the  powder  on  a  filter,  first  with 
cold  water,  then  with  alcohol  containing  sulphuric  acid, 


§  136.     MILK.  263 

to  take  out  the  gluten,  and  again  with  water ;  then  pierce 
the  filter  with  the  glass  rod,  wasli  its  contents  into  a  flask, 
tear  the  filter  into  shreds,  and  boil  it  by  itself  with  water 
CQntaining  4  or  5  drops  of  20"  1^  sulphuric  acid,  and  finally 
add  it  to  the  contents  of  the  flask ;  the  total  amount  of 
solution  thus  obtained  should  not  be  over  100  c.c. ;  pro- 
ceed as  usual  with  the  conversion  of  the  starch  into  glu- 
cose (§  79). 

In  most  seeds  there  is  bnt  little  gnm  or  sugar ;  one  can 
therefore  proceed  at  once  to  treat  the  seeds  with  alcohol 
acidified  with  sulphuric  acid,  as  above,  remove  the  alcohol 
by  heat,  and  convert  the  starch  into  glucose. 

MILK. 

136.  a.  Water. — Boil  50  grms.  of  the  milk  with  8 
grms.  of  powdered  crystalline  gypsum,  or  with  30-40 
grms.  of  baric  sulphate  (§  90,  A),  and  after  the  coagula- 
tion has  taken  place,  evaporate  the  mixture  to  dryness  on 
the  water-bath,  with  constant  stirring  towards  the  end  of 
the  operation,  and  dry  the  residue  at  100°  as  long  as  it 
loses  weight. 

Or,  the  desiccation  may  be  completed  on  hot  sand  in 
rarefied  air  (§  90,  g). 

h.  Total  non-YOlatile  matter. — Evaporate  30  grms.  of 
the  milk  to  dryness,  with  the  addition  of'  a  little  acetic 
acid,  and  incinerate  the  residue  in  the  muffle  at  the  lowest 
j)ossible  temperature. 

c.  Protein  compounds. — These  may  be  estimated  by 
the  remainder  left  after  subtracting  the  sugar,  butter,  and 
ash,  from  the  total  dry  substance ;  this  residue  consists 
mostly  of  casein.  Or,  nitrogen  may  be  estimated  in  the 
usual  manner  (§  85)  iu  the  residue  left  on  evaporating  6-7 
grms.  of  the  milk  to  dryness  with  powdered  gypsum  or 
baric  sulphate,  as  above. 

Albumen  is  contained  iu  milk  in  but  small  proportion ; 


264  §    136.       FODDER   AND   FOOD. 

in  the  case  of  some  diseases,  it  occurs  in  larger  quantity. 
To  estimate  it,  coagulate  100  grms.  of  the  milk  with  ren- 
net, at  a  temperature  of  about  45°  C,  filter  out  the  pre- 
cipitate, and  wash  it,  and  heat  the  filtrate  and  washings 
to  boiling.  Collect  the  precipitated  albumen  on  a  dried 
and  weighed  filter,  dry  it  at  100  C,  and  weigh  it. 

d.  Butter. — Extract  the  residue  obtained  in  a  with 
ether  (§  87). 

Various  other  and  shorter  processes  are  given  for  tes-t- 
ing  the  goodness  of  milk  in  this  respect,  in  one  of  which 
the  cream  is  estimated  by  volume. 

Provide  a  shallow  glass  dish  in  the  form  of  an  inverted 
bell-jar,  with  a  ground  glass  plate  to  cover  it  and  prevent 
evaporation  of  the  milk,  and  a  narrow  orifice  below,  closed 
with  a  glass  stopper ;  a  graduated  cylinder  holding  100 
c.c.  will  also  be  needed. 

Put  100  c.c.  of  cooled  milk  into  the  dish,  and  let  it  stand 
24  hours,  at  a  temperature  of  12-15°  C. ;  then  loosen  the 
stopper  below,  and  let  the  milk  flow  out  from  underneath 
the  cream  into  the  graduated  cylinder.  After  about  ^  |^ 
of  the  milk  has  run  out,  stop  the  flow  for  a  few  minutes, 
to  allow  the  cream  to  collect  together  somewhat,  and  then 
let  the  milk  flow  out  again,  but  only  drop  by  drop,  until 
the  cream  appears  at  the  opening  ;  the  quantity  by  which 
the  milk  now  collected  in  the  cylinder  is  less  than  the 
original  100  c.c.  represents  the  cream,  and  the  percentage 
of  cream  by  volume  can  be  estimated.  1"!  ^  by  volume 
corresponds  very  nearly  to  one-fourth  "[^  of  butter  in  the 
milk,  by  weight. 

If  a  glass  dish,  like  that  described  above,  cannot  bo 
obtained,  any  shallow  dish  that  can  be  well  covered  will 
answer,  and  the  milk  can  be  withdrawn  from  under  the 
cream  by  a  small  siphon,  with  a  rubber  tube  and  clamp 
at  the  end  of  the  longer  arm  to  regulate  the  flow  of  the 
liquid. 


§  136.     MILK.  265 

VogePs  optical  milk  test. — This  j^rocess  meets  with 
very  general  acceptance.  It  depends  upon  the  fact  that 
the  light  is  intercepted  by  water  containing  a  smaller 
proportion  of  milk,  the  richer  the  milk  is  in  butter. 

The  apparatus  required  consists  of  a  measuring  flask, 
with  a  mark  on  the  neck,  indicating  a  capacity  of  100  c.c, 
a  test-glass,  for  holding  a  sample  of  the  milk  and  water 
between  the  eye  and  the  light,  which  should  have  parallel 
glass  sides,  ^\  ^  cm.  apart,  so  that  the  thickness  of  the  layer 
of  milk  looked  through  will  be  exactly  ^  l^  cm.,  a  pipette 
graduated  in  ^  1^  cubic  centimetres,  and  holding  4-5  c.c, 
and  a  box  about  16  cm.  long  and  wide,  with  a  slit  in  one 
side,  in  front  of  which,  and  40  cm.  distant,  the  stearin 
candle  is  placed ;  the  opposite  side  of  this  box  is  so  cut 
out  to  fit  the  face  that,  when  the  glass  containing  the 
milk  is  put  in  the  box,  all  light  can  be  excluded  while  an 
observation  is  made,  except  that  coming  through  the  slit 
from  the  candle  ;  the  inside  of  the  box  should  be  painted 
black. 

To  perform  the  test,  fill  the  100  c.c.  flask  with  distilled 
water  up  to  the  mark,  add  to  it  3  c.c.  of  the  well-stirred 
sample  of  the  cooled  milk,  and  mix  the  two  together 
thoroughly  by  vigorous  agitation  ;  fill  the  test-glass  with 
this  mixture,  put  it  in  the  dark  box,  and  make  the  obser- 
vation, placing  the  eye  close  to  the  test-glass,  and  the 
candle  against  a  dark  background.  If  the  light  can  be 
seen,  pour  the  test  sample  back  into  the  flask,  add  ^  1^  c.c. 
more  of  milk,  and  make  another  observation ;  continue'to 
operate  in  this  manner,  adding  ^  1^  or  ^  \^  c.c.  of  milk  each 
time,  until  the  light  is  no  longer  visible. 

The  relation  between  the  number  of  cubic  centimetres 
of  milk  required  and  the  per  cent  of  butter  is  given  in 
Table  IX.  This  per  cent  is  calculated  by  the  formula 
23:2  _j_  0.23,  in  which  7/  =  the  number  of  cubic  centimetres 
of  milk  required.  If  5.5  c.c.  or  more  of  milk  were  used 
to  produce  opacity,   it  is    prob^fele  that  the    milk  "^as 

12 


266  §    136.       FODDER    AT^D    FOOD. 

watered.     It  is  rare  that  less  than  3  c.c.  of  cow's  milk  will 
be  needed. 

e.  Sugar. — Collect  the  residue,  insoluble  in  ether,  in  d^ 
on  a  dried  and  weighed  filter,  dry  it  at  100°  C,  boil  it  four 
or  five  times  Avith  fresh  portions  (150  c.c.  each)  of  80°  |„ 
alcohol,  and  weigh  this  insoluble  residue  on  a  dried  and 
weighed  filter,  after  drying  it  at  100°  C.  The  loss  of 
weight,  after  extraction  with  alcohol,  gives  the  lactose 
approximately.  The  residue  on  the  filter  will  be  mainly 
casein  and  insoluble  salts,  together  with  the  baric  sul- 
phate or  gypsum,  with  which  the  milk  was  evaporated. 

Or,  to  determine  the  lactose  more  accurately,  dilute  20 
grms.  of  the  milk  with  twice  its  volume  of  water,  heat 
the  liquid  to  40°  C,  coagulate  the  casein  with  4  drops  of 
acetic  acid,  collect  the  coagulum  on  a  linen  filter,"  and 
wash  it  well  with  water.  Dilute  the  filtrate  and  washings 
to  200  c.c,  and  determine  lactose  in  the  usual  manner,  in 
a  measured  volume  of  the  liquid,  previously  filtered  if 
necessary  (§  84). 

f.  Lacto-protein,  hutter,  casein^  etc,  —  Millon  and 
Commaille  give  this  process  for  estimating  the  protein 
compound  peculiar  to  milk,  and  for  the  determination  of 
other  substances  also. 

Dilute  20  grms.  of  milk  with  4  volumes  of  water,  add 
5-6  drops  of  acetic  acid,  stir  the  mixture  well,  filter  out 
the  coagulum,  wash  it  two  or  three  times  on  the  filter  with 
a^  little  water  as  possible,  and  then  with  40"  |  „  alcohol. 
Separate  the  precipitate  from  the  filter,  diffuse  it  in  abso- 
lute alcohol,  collect  it  again  on  a  dried  and  weighed  filter, 
and  extract  the  butter  by  ether  containing  '(^^  of  abso- 
lute alcohol,  that  is  poured  over  the  contents  of  the  filter. 
Evaporate  the  etherial  extract,  to  estimate  the  butter  taken 
into  solution,  and  dry  the  casein  on  the  filter  at  100°  C, 
and  weigh  it. 

Heat  half  the  filtrate  from  the  first  coagulum,  or  the 


§    137.       BUTTEIl.       CHEESE.  267 

whey,  to  boiling,  filter  out  the  coagulated  albumen  on  a 
dried  and  weighed  filter,  wash  it  first  with  water,  then 
with  alcohol,  and  finally  with  ether,  dry  it  at  100°  C,  and 
weigh  it. 

To  the  filtrate  add  a  solution  of  mercuric  nitrate,  with 
care  to  avoid  an  excess  of  the  reagent.  Lacto-protein  is 
precipitated,  together  with  mercuric  oxide;  collect  the 
precipitate  on  a  weighed  filter,  wash  it  once  with  water 
containing  1°!^  of  nitric  acid,  then  with  pure  water  as 
long  as  the  filtrate  is  colored  by  hydrosulphuric  acid,  then 
with  alcohol,  and  finally  with  ether;  finally  dry  it  at  100° 
C,  and  weigh  it.  60"  1^  of  it  is  to  be  estimated  as  lacto- 
protein. 

Determine  milk  sugar  in  one-fourth  of  the  whey  (§  84). 

Evaporate  the  remaining  fourth  to  dryness  in  a  plati- 
num dish,  dry  the  residue  at  100°,  and  weigh  it,  ignite  it, 
and  weigh  again.  Subtract  the  ash,  albumen,  lacto-pro- 
tein, and  milk  sugar,  from  the  total  amount  of  matter  in 
solution  in  the  whey,  and  call  the  remainder  undetermined 
extractive  matter. 

BUTTER.     CHEESE. 

137.  a.  Water. — Dry  50  grms.  of  the  finely  divided 
substance  at  100°  C.  as  long  as  it  loses  weight ;  butter  is 
more  easily  dried  if  a  weighed  quantity  of  quartz  sand 
is  mixed  with  it. 

h.  Fat. — Extract  this  with  ether  in  the  usual  manner 
(§  87),  collecting  the  insoluble  residue  on  a  weighed  filter. 

c.  Casein. — Wash  the  residue,  insoluble  in  ether,  well 
with  Avater,  evaporate  the  aqueous  solution  to  dryness, 
dissolve  the  residue  again  in  water,  and,  if  any  of  it  is 
insoluble,  collect  this  on  the  same  filter,  and  wash  the 
whole  again;  dry  the  contents  of  the  filter  at  100°,  and 
weigh,  ignite,  and  weigh  again,  and  call  the  difference 
between  the  first  and  second  weighings,  casein. 


268  §    138.       FODDER   AND   FOOD. 

d.  Salt. — By  evaporating  the  aqueous  extract  obtained 
in  the  preceding  operation,  or  an  aliquot  part  of  it,  to  dry- 
ness, and  igniting  and  weighing  the  residue,  the  amount 
of  salt  in  the  butter  or  cheese  may  be  estimated. 

VINEGAR. 

188.  The  only  constituent  of  vinegar  which  it  is  usually 
desired  to  estimate  quantitatively  is  the  acetic  acid. 

a.  For  this  estimation,  i^roceed  as  directed  in  §  70. 
Good  vinegar  should  contain  about  5°  |  ^  of  this  acid. 

The  vinegar  should  give  no  reaction  for  sulphuric  or 
hydrochloric  acid,  after  acidification  with  nitric  acid.  If 
it  has  been  adulterated  with  these  acids,  they  will  of 
course  saturate  a  portion  of  the  standard  sodic  solution. 

h.  Free  sulphuric  acid  in  vinegar  may  be  detected  and 
determined  by  adding  baric  carbonate  to  it,  filtering, 
washing  the  contents  of  the  filter,  and  then  treating  the 
residue  with  hydrochloric  acid ;  the  excess  of  baric  car- 
bonate that  was  used  will  be  dissolved  by  the  acid,  while, 
if  mrj  free  sulphuric  acid  was  present,  baric  sulphate  will 
remain  undissolved ;  it  may  be  washed  and  weighed  in 
the  usual  mamier  (§  59). 


§  139.     WOOL.  269 

CHAPTER  IX. 

WOOL. 

139i  a.  The  sample  for  examination.— Take  a  sample 
from  each  one  of  several  sheep  just  before  the  time  of 
shearing,  and  after  the  animals  have  been  washed  in  the 
customary  manner,  and  from  the  following  parts  of  each 
animal — the  leaf,  the  side,  the  middle  of  the  chine  bone, 
the  withers,  the  neck  close  to  the  nape,  the  middle  of  tlie 
thigh,  and  the  middle  of  the  belly ;  each  specimen  should 
be  taken  from  a  spot  an  inch  in  diameter,  and  be  cut  off 
close  to  the  skin,  put  at  once  in  a  large  glass  tube  of 
known  weight,  that  can  be  well  stoppered,  and  weighed 
when  taken  to  the  laboratory.  The  number  of  the  par- 
ticular animal  and  the  spot  from  which  the  sample  was 
taken  should  be  marked  on  a  label  on  each  tube. 

If  the  wool  is  to  be  examined  with  respect  to  its  phys- 
ical properties,  or  by  one  who  is  experienced  in  handling 
it  and  judging  its  value,  two  other  samples  should  be 
taken  from  each  animal,  and  from  the  same  spots,  one 
before  the  washing,  and  the  other  afterwards,  and  all 
samples  should  be  preserved  and  labeled  in  the  manner 
prescribed  above. 

The  sample  from  each  part  of  the  animal  is  to  be  exam- 
ined by  itself,  but  if  it  is  desired  to  determine  only  the 
average  quality  of  the  wool  of  the  flock,  the  several  sam- 
ples from  like  parts  of  the  different  sheep  may  be  exam- 
ined together. 

If  a  sample  of  unwashed  wool  is  to  be  examined, 
weigh  each  one,  determine  the  water  in  a  small  portion 
by  desiccation  at  100°,  and  wash  the  other  portion  gently 
in  cold,  soft  water  until  the  water  is  no  longer  made  tur- 
bid, dry  it,  and  weigh  it  in  the  air-dried  state.  The 
subsequent  treatment  is  the  same  as  for  the  washed  wool. 


270  §  140.     WOOL. 

h.  Water. — Dry  3-4  grms.  at  100°  C,  and  weigh  it. 

c.  Wash  a  quantity  of  the  wool  in  a  manner  similar 
to  that  practiced  in  the  factory.  For  this  purpose  pre- 
l^are  a  solution  of  3  parts  of  hard  soap  and  2  of  crys- 
tallized sodic  carbonate,  in  100  of  distilled  or  rain-water, 
heat  20  parts  of  this  solution  to  50-55°,  put  1  part  of 
wool  in  it,  and  stir  the  mixture  gently  for  15  or  20 
minutes,  while  the  solution  is  maintained  at  the  same 
temperature ;  then  take  the  wool  out,  wash  it  in  severaj 
portions  of  water,  dry  it  in  the  air,  spread  it  out  on  fine 
wire  gauze,  tap  the  gauze  gently  underneath  several  times, 
pick  off  adhering  particles  of  foreign  matters  with  the 
pincettes,  dry  the  residue  at  100°  C,  and  weigh  it.  If, 
after  this  treatment,  the  wool  still  feels  greasy,  it  should 
be  washed  again  in  a  somewhat  stronger  bath.  Finally 
extract  any  remaining  fat  with  carbonic  disulphide  or 
ether,  dry  the  residue  again  at  100°,  and  weigh  it. 

d.  Treat  another  portion  of  the  wool  in  the  reverse 
manner,  that  is,  first  with  ether  (§  87),  and  then,  after 
drying  and  weighing  the  residue,  wash  it  in  the  bath  of 
soap  and  soda.  Determine  the  fat  in  the  etherial  solu- 
tion, or  an  aliquot  part  of  it. 

e.  Determine  the  ash  in  the  residue  of  c  and  d  in  the 
usual  manner  (§  127).  Examine  this  ash  for  sand  by 
digestion  with  hydrochloric  acid,  and  boiling  with  sodic 
carbonate  (§  58). 

f.  To  determine  the  specific  gravity  of  the  j^ure  wool 
obtained  in  c  and  J,  weigh  it  first  in  air  and  then  in  car- 
bonic disulj^hide  of  knoAvn  specific  gravity  (§  35,  5,  d). 

TANNER'S  BARK. 

140.  a.  Preparation  of  the  sample.— Cut  the  bark  to 
be  examined,  lengthwise,  in  very  thin  shavings. 
h.  Water.— Desiccate  1-2  grms.  at  100°  C. 
c.  Tannic  acid,— Pour  100  c.c.  of  Avater  over  the  dried 


§    141.       WATER.  271 

substance  obtained  in  b,  and  digest  the  mixture  in  a  flask, 
15  minutes  at  a  boiling  heat,  filter,  and  repeat  the  same 
operation  twice  with  the  residue.  Evaporate  this  aque- 
ous extract  to  dryness  on  the  water-bath,  with  the  addi- 
tion of  a  few  drops  of  acetic  acid,  extract  the  residue 
with  strong  alcohol,  filter  the  liquid,  evaporate  the  filtrate 
until  the  alcohol  is  expelled,  and  dissolve  the  residue  in 
distilled  water;  by  this  treatment  pectose  is  removed 
from  the  aqueous  extract.  Determine  tannic  acid  in  the 
solution  finally  obtained  (§  77). 


CHAPTER    X. 
BEVERAGES. 

I. 

WATER. 

141.  For  a  complete  analysis  of  water,  we  must  refer 
to  Fresenius's  Quantitative  Analysis  for  directions,  while 
we  confine  ourselves  here  to  such  special  determinations 
as  possess  a  more  direct  domestic  or  agricultural  interest. 

a.  Total  Dry  Substance  in  Solution. — Evaporate  500 
grms.  of  the  water  to  dryness,  in  a  platinum  dish,  at  a 
temperature  at  all  times  below  boiling ;  dry  the  residue 
at  130°  C,  and  weigh  it ;  ignite  it,  moisten  the  residue  two 
or  three  times  with  a  concentrated  solution  of  ammonic 
carbonate,  drying  it  each  time  cautiously ;  finally  ignite 
the  residue  gently,  and  weigh  the  total  non-volatile  dry 
substance. 

Or,  instead  of  treatment  with  ammonic  carbonate,  dis- 
solve the  ignited  residue  in  water  in  the  crucible,  pass  a 


272  §    141.       BEVEKAGES. 

slow  current  of  carbonic  acid  through  it  for  a  while,  and 
dry  the  residue  for  a  considerable  time  at  150-180°. 

This  determination  of  organic  matter  in  water  is  con- 
sidered by  some  good  chemists  as  possessing  no  great  value. 

h.  Potassa* — The  estimation  of  this  in  water  used  for 
irrigation  is  sometimes  important.  For  this  purpose, 
evaporate  2000-4000  c.c.  of  the  water  to  dryness,  elimi- 
nate the  silica  in  the  usual  way,  and  the  alkalies  as  chlo- 
rides in  the  filtrate  from  the  silica  (§  93,  G). 

c.  Ammonia. — To  determine  this  in  rain-water,  evapo- 
rate 2000-3000  c.c.  down  to  200  c.c,  after  acidifying  the 
water  very  slightly  with  hydrochloric  acid,  add  an  excess 
of  freshly  prejDared  sodic  hydrate,  or  of  baric  hydrate,  to 
the  residue,  and  distil  the  ammonia  off  in  the  usual  man- 
ner (§  47,  c). 

Deteraiine  the  ammonia  in  the  distillate  with  the  aid  of 
platinic  chloride,  or  by  the  indirect  process  with  the 
Nessler  solution. 

To  insure  greater  accuracy,  the  whole  operation  should 
be  repeated  without  the  water,  and  with  the  same  amount 
of  sodic  or  baric  hydrate  and  platinic  chloride  or  Nessler's 
solution ;  if  any  ammonia  is  thus  found,  it  is  due  to  im- 
purities in  the  reagents,  and  should  be  subtracted  from 
the  amount  obtained  in  the  first  experiment. 

If  the  water  is  a  colored  one,  derived  from  some  other 
source,  add  calcic  chloride,  sodic  carbonate,  and  a  few 
drops  of  potassic  hydrate  before  distilling. 

d.  Nitric  Acid, — Evaporate  2000-4000  c.c.  of  the  water, 
after  having  added  some  sodic  carbonate,  filter  out  the 
precipitate,  if  any  is  formed,  wash  it  well,  evaporate  the 
filtrate  and  washings  to  a  small  bulk,  and  determine  the 
acid  by  Schlossing's  process  (§  62,  a). 

e.  Organic  Matter.— Evaporate  100  c.c  of  the  water 
down  to  about  60  c.c,  in  a  flask  of  500  c.c.  capacity,  in 
order  to  decompose  ammoniacal  compounds  by  the  caTcic 


§    141.      WATER.  273 

carbonate  that  is  nearly  always  present,  add  water  till 
the  original  volume  is  about  restored,  and  proceed  to 
titrate  the  solution  for  the  organic  matter  with  potassic 
permanganate  (§  91). 

A  good  drinking  water  should  not  contain  more  than 
3-4  parts  of  organic  matter  in  100,000  parts. 

If,  on  adding  to  100  c.  c.  of  the  water  2  or  3  drops  of 
concentrated  sulphuric  acid  and  a  little  of  a  freshly  pre- 
pared mixture  of  potassic  iodide  and  boiled  starch,  the 
water  is  colored  blue,  nitrous  acid  is  present,  and  a  correc- 
tion must  be  made  in  the  determination  of  the  organic 
matter.  For  this  purpose  add  10  c.c.  of  the  dilute  sul- 
phuric acid  to  100  c.c.  of  the  water,  and  then  add  joer- 
manganic  solution  till  the  first  trace  of  a  red  color  appears. 
The  aniount  of  the  standard  solution  required  for  this 
must  be  subtracted  from  the  total  amount  required  in  the 
first  trial. 

The  presence  of  nitrous  acid  in  drinking  water  should, 
however,  be  regarded  with  suspicion,  for  it  indicates  that 
the  water,  perhaps,  contained  nitrogenous  organic  matter, 
from  which  it  may  not  yet  be  entirely  freed ;  such  organic 
matter  is  far  more  harmful  than  that  containing  no  nitrogen. 

Other  prominent  methods  of  making  this  important 
determination  of  organic  matter,  and  particularly  nitrog- 
enous matter,  in  water,  have  not  yet  been  sufficiently 
tested  to  justify  their  insertion  here,  although,  without 
doubt,  good  methods  will  soon  be  worked  up  out  of  the 
material  now  in  hand.  Many  good  chemists  still  allow 
some  value  to  the  indications  that  are  furnished  by  the 
permanganic  test  relative  to  the  badness  of  the  water  in 
sanitary  respects,  while  others  have  no  confidence  in  it. 
Other  substances  besides  nitrous  acid  may  increase  the 
amount  of  permanganic  solution  that  is  reduced,  and  so 
give  too  large  an  amount  of  organic  matter,  as  ferrous  sul- 
phate, for  instance. 

f.  Lime* — To  determine  this  base,  which,  in  one  form  or 
12* 


2T4  §    141.       BEVERAGES. 

another,  is  the  source  of  the  largest  part  of  the  hardness 
of  water,  add  a  little  hydrochloric  acid  to  100-500  c.c, 
heat  the  mixture,  and  precipitate  and  determine  lime  with 
the  aid  of  aramonic  oxalate,  in  the  usual  manner  (§  49,  a). 

Or,  by  a  more  speedy  though  somewhat  less  accurate 
method,  to  100  c.c.  of  the  water  in  a  300  c.c.  flask,  add 
25  c.c,  or,  if  the  water  is  very  hard,  50  c.c.  of  a  ^  \^^  atomic 
solution  of  oxalic  acid,  then  add  ammonia  until  the 
reaction  of  the  liquid  is  faintly  alkaline,  and  heat  the 
mixture  until  it  boils. 

After  the  liquid  has  cooled,  add  distilled  Avater  up  to 
the  300  c.c.  mark,  mix  the  whole  well  together,  filter  the 
liquid  through  an  unmoistened  filter  into  a  dry  glass, 
putting  the  first  portions  of  the  filtrate  on  the  filter  again, 
if  turbid,  as  is  often  the  case.  To  200  c.c.  of  the  clear 
filtrate,  in  a  capacious  flask,  add  10  c.c.  of  concentrated 
'sulphuric  acid,  heat  the  solution  to  50-60°  C,  and  deter- 
mine the  excess  of  oxalic  acid  in  it  with  the  aid  of  the 
standard  permanganic  solution  (§  69).  By  multiply- 
ing the  number  of  cubic  centimetres  of  the  standard 
solution  used  by  1.5,  the  amount  that  would  have  been 
required  for  the  whole  solution  is  obtained.  Each  cubic 
centimetre  of  the  solution  of  oxalic  acid  that  did  not 
require  to  be  decomposed  by  the  permanganate,  was 
engaged  in  the  precipitated  calcic  oxalate,  and  corre- 
sponds to  0.0028.  grm.  of  lime. 

g.  Hardness  of  the  Water.— 1.  ClarJc's  method.  This, 
though  a  convenient  method  of  determining  the  hardness 
of  water,  does  not  give  highly  accurate  results ;  it  is, 
however,  generally  used. 

The  scale  of  hardness  is  expressed  by  the  number  of 
milligrammes  of  lime  in  100,000  mgrs.,  or  100  grms.  of 
water,  that  are  required  to  produce  the  different  degrees 
of  hardness,  and  this  hardness  is  estimated  by  the  amount 
of  soap  precipitated  from  a  standard  solution  of  the 
same. 


§    141.      WATEE.  275 

The  Standard  Solution  of  Soap. — Mix  together  150 
parts  of  lead  plaster  and  40  parts  of  potassic  carbonate, 
exhaust  the  mass  with  alcohol,  filter  the  liquid,  evaporate 
the  filtrate  on  the  water-bath,  and  dissolve  the  residue  in 
50  parts  of  56"  |^  alcohol.  Dissolve,  also,  0.523  grm.  of 
pure  and  dry  baric  chloride  in  water,  and  dilute  the  solu- 
tion to  one  litre. 

Provide  a  bottle  of  about  200  c.c.  capacity,  with  a  well- 
fitting  glass  stopper,  and  a  mark  on  the  side  to  indicate  a 
capacity  of  100  c.c,  put  100  c.c.  of  the  solution  of  baric 
chloride  in  this  bottle,  and  add  the  solution  of  soap  from 
a  burette  or  a  graduated  pipette,  with  frequent  agitation, 
until  an  abundant  delicate  lather  appears  that  lasts  five 
minutes.  The  shaking  of  the  bottle  should  always  be 
performed  in  the  same  manner  ;  the  best  way  is  to  grasp 
the  stopper  and  the  neck  with  one  hand,  and  the  bottom 
with  the  other,  and  shake  it  up  and  down. 

Having  tested  the  strength  of  the  solution  of  soap, 
dilute  it  with  56"  1^  alcohol  to  such  an  extent  that  45  c.c. 
are  necessary  to  produce  the  lather  with  100  c.c.  of  the 
solution  of  baric  chloride  ;  this  quantity  of  the  latter 
solution  produces  the  same  degree  of  hardness  as  12 
mgrs.  of  lime. 

Exammation  of  a  Sample  of  Water.— If  a  hard  spring 
water  is  to  be  examined,  put  10  c.c.  of  it  into  the  bottle 
described  above,  and  add  distilled  water  up  to  the  100  c.c. 
mark ;  if  it  is  a  soft  river  water,  fill  the  bottle  up  to  this 
mark  with  the  water  alone ;  then  add  the  solution  of  soap 
from  the  burette,  as  above.  Add  at  first  larger  quantities  of 
the  standard  solution  at  a  time,  but,  towards  the  close, 
the  agitation  should  be  repeated  -after  each  0.5  or  1  c.c. 
that  is  added,  and  finally  between  each  drop  or  two. 

On  repeating  the  experiment,  in  case  but  little  of  the 
standard  solution  was  used,  take  25  to  50  c.c.  of  the  water, 
but  not  a  quantity  that  will  require  more  than  45  c.c.  of 
the  standard  solution  ;  in  this  second  trial  add,  at  once, 


276  §    141.       BEVERAGES. 

all  but  1-2  c.c.  of  the  solution  of  soap  that  will  be 
required,  and  then  allow  it  to  flow  in  drop  by  drop  only, 
until  the  reaction  is  ended. 

The  relation  between  the  quantity  of  the  standard  solu- 
tion used  and  the  hardness  of  the  water  is  given  in  Table 
YIII.  If  the  water  tested  was  diluted  with  distilled  water, 
the  hardness  is  to  be  taken  as  many  times  greater  as  the 
volume  of  the  water  was  increased  by  the  dilution. 

If  a  water  contains  more  than  12  parts  of  lime  in 
100,000,  the  first  addition  of  the  solution  of  soap  to  it 
causes  the  formation  of  a  flocculent  precipitate,  and  it 
must  be  diluted  as  above  before  the  test  is  made  ;  if  less 
than  this  proportion  of  lime  is  present,  only  an  opalescence 
appears  in  the  liquid  on  adding  a  drop  of  the  solution  of 
soap. 

"With  respect  to  the  hardness  of  water,  we  have  to  dis- 
tinguish the  total  hardness^  which  is  caused  by  the  total 
amount  of  lime  in  the  water,  and  \hQ  permanent  hardness, 
caused  by  salts  of  lime  that  are  not  precipitated  when  the 
liquid  is  boiled,  such  as  calcic  sulphate  and  chloride.  To 
determine  this  permanent  hardness,  boil  300  to  500  c.c.  of 
the  water  half  an  hour,  in  a  flask  of  twice  the  capacity, 
replacing  the  water,  as  it  is  evaporated,  by  fresh  distilled 
water ;  after  the  liquid  has  cooled,  make  its  volume  the 
same  as  that  with  which  the  operation  was  begun,  by 
adding  more  water,  mix  the  whole  well  together,  filter 
the  liquid,  and  determine  the  permanent  hardness  in  an 
aliquot  part  of  it,  as  above. 

2t  FlecTc's  method. — This  apparently  convenient  method 
depends  upon  the  fact  that,  when  a  solution  of  soda-soap 
in  alcohol  is  added  to  a  solution  of  a  calcic  salt,  a  neutral 
sodic  salt  is  formed,  and  that,  as  soon  as  all  the  calcic  salt 
is  decomposed,  the  addition  of  more  soda-soap  will  turn 
red  litmus  blue.  (Freeenius^s  Zeltschrift,  7,  351.) 
.    TJie  Standard  Solutions. — Solittio?i  of  Soap. — Cut  50 


§    141.       WATER.  277 

grms.  of  pure  Marseilles  soap  in  tliin  slices,  pour  500  c.c. 
of  74"  Iq  alcohol  over  it,  and  heat  the  mixtures  ;  the  soap 
should  he  free  from  sodic  carbonate  or  hydrate,  and  its 
solution  should,  therefore,  give  no  precipitate  or  black 
color  Avith  mercurous  nitrate.  Filter  the  solution,  if  it  is 
not  perfectly  clear.  PrejDare  a  saturated  solution  of  calcic 
sulphate,  and  to  100  c.c.  of  it  add  10  drops  of  a  solution 
of  litmus  (or  cochineal)  ;  boil  the  liquid  five  minutes  and 
add  the  standard  nitric  acid  from  a  burette,  drop  by  drop, 
until  the  blue  color  is  changed  to  red  ;  then  add  the  solu- 
tion of  soap  from  another  burette  until  the  blue  color 
reappears. 

The  solution  of  soap  is  now  to  be  made  of  such  a 
strength  that  20  c.c.  of  it  will  be  required  to  produce  the 
blue  color,  with  100  c.c.  of  the  solution  of  calcic  sulphate. 
If,  for  example,  15  c.c.  were  required  in  the  above  experi- 
ment, 5  c.c.  of  alcohol  must  be  added  to  every  15  of  the 
solution  of  soap  to  make  the  standard  solution. 

100  c.c.  of  tlie  saturated  solution  of  gypsum  contain 
210  mgrs.  of  calcic  sulphate  ;  eacli  cubic  centimetre  of 
the  soap  solution,  representing  1°  of  hardness,  corre- 
sponds, therefore,  to  l2  mgrs.  of  calcic  sulphate. 

The  standard  nitnc  acid  is  conveniently  made  of  such 
a  strength  that  0.1  c.c.  neutralizes  1  c.c.  of  the  standard 
solution  of  soap.  0.05  c.c.  of  nitric  acid,  corresponding  to 
0.5°  of  hardness,  has  to  be  used  in  excess  to  produce  a 
permaAent  red ;  therefore,  0.5  should  be  subtracted  from 
the  total  amount  of  soap  solution  used. 

Examination  of  a  Sample  of  Water. — If  the  water 
contains  calcic  carbonate,  boil  100  c.c.  in  a  beaker  or 
flask,  until  the  carbonate  is  precipitated ;  then,  without 
filtering,  add  10  droj^s  of  litmus  solution  (or  cochineal), 
and  add  the  nitric  acid  precisely  as  in  estimating  the 
strength  of  the  solution  of  soap,  as  first  made ;  the  litmus 
will  not  be  colored  permanently  red  until  all  the  calcic 
carbonate  is  dissolved ;    therefore,  the  number  of  cubic 


278  §    143.       BEVERAGES. 

centimetres  of  acid  required  for  this  represents  the  tem- 
porary hardness.  After  adding  the  proper  quantity  of 
nitric  acid,  j^roceed  to  add  the  standard  solution  of  soap, 
in  the  same  manner  as  when  determining  the  strength  of 
this  solution  with  the  aid  of  calcic  sulphate. 

Suppose  that,  in  treating  100  c.c.  of  the  water  in  this 
manner,  0.2  c.c.  of  nitric  acid  were  required  to  produce  a 
permanent  red  color,  and  8  c.c.  of  the  solution  of  soap  to 
change  the  red  to  blue;  2  c.c.  of  the  latter  were  necessary 
to  decompose  the  calcic  nitrate  resulting  from  the  actioii 
of  the  0.2  c.c.  of  nitric  acid  on  the  calcic  carbonate,  and 
6  c.c.  to  decompose  the  calcic  sulphate ;  subtracting  0.5 
c.c,  as  above  directed,  for  the  excess  of  nitric  acid,  we 
have  2°  for  the  temporary  hardness,  and  5.5°  for  the  per- 
manent hardness  of  the  water  examined. 

10°  of  hardness  indicates  a  hard  water ;  the  hardness  of 
river  water  is  usually  from  2°  to  6°. 


II. 

WINE. 

142.  a.  Specific  Gravity.— Determine  this  carefully 
with  the  specific-gravity  bottle. 

1).  Dry  Substance  ia  Solution. — Evaporate  20  grms. 
to  dryness  with  gypsum  (§  90,  h). 

c.  Total  IVon-volatilc  Matters.— Evaporate  200-500 
grms.  to  dryness  on  the  water-bath,  and  incinerate  the 
residue  in  the  usual  manner ;  determine  carbonic  acid  in 
the  ash. 

d.  Complete  Analysis  of  the  Ash.— This  is  rarely  im- 
portant, but  may  be  made  according  to  Scheme  I.,  §  94. 

e.  Protein  Compounds.— Evaporate  100  grms.  with 
gypsum  (§  90,  A),  and  ignite  the  residue  with   soda-lime 

(§  85). 


§  142.     WINE.  279 

/.  Alcohol*  —Estimate  this  in  10  or  25  c.c.  of  the  wine, 
adding  a  few  drops  of  soda,  or  enough  to  change  the 
color  of  the  wine  completely,  and  about  0.06  grm.  of 
tannin ;  the  soda  neutralizes  the  free  acid,  and  the  tannic 
acid  prevents  frothing.  For  the  manner  of  conducting 
the  distillation,  see  §  87. 

g.  Sugar. — This  may  be  determined  in  100  grms.  of 
the  wine  directly,  in  the  usual  manner  (§  81),  after  decol- 
oiizing  the  liquid  by  contact  with  2-3  grms.  of  bone-black, 
and  filtering. 

Or,  the  wine  may  be  decolorized  iu  this  manner 
(Grifiin).  Dilute  the  red  wine  to  about  half  the  extent 
required  for  the  determination  of  srtgar,  add  enough  milk 
of  lime  to  make  the  liquid  alkaline,  and  agitate  the  mix- 
ture well ;  then  add  about  one-tenth  as  much  of  a  solution 
of  basic  plumbic  acetate  as  was  taken  of  the  wine,  and 
shake  the  mixture  again ;  finally  add  one-third  as  much 
of  a  solution  of  alum,  containing  1  part  of  salt  in  20  of 
water,  as  was  required  of  the  plumbic  solution,  dilute  the 
mixture  to  any  volume  easily  divisible  into  aliquot  j^arts, 
mix  the  whole  together  by  violent  agitation,  let  it  stand 
until  the  solid  matters  settle,  and  then  decant  enough  of 
the  supernatant  liquid  into  a  dry  filter  for  the  determina- 
tion of  the  sugar. 

If  the  wine  is  a  light-colored  one,  nothing  need  be 
added  but  sodic  carbonate  until  it  is  alkaline. 

Cane  sugar  exists  in  wine  only  when  it  has  been  pur- 
posely added.  It  can  be  estimated,  if  present,  in  the 
usual  way  (§  83). 

If  the  wine  is  neutralized  with  lime,  and  alcohol  added 
to  precipitate  malic  and  succinic  acids,  a  little  baryta- 
water  will  give  a  precipitate  in  the  filtrate,  which  is  more 
or  less  abundant,  according  to  the  amount  of  sugar  pres- 
ent (§  83). 

h.  Gum  (and  sugar),  etc. — Evaporate  100  grms.  of  the 
wine  to  a  syrup  on  the  water-bath,  exhaust  the  residue 


280  §    142.       BEVERAGES. 

by  digestion  with  several  portions  of  alcohol,  as  long  as 
a  fresh  portion  is  colored,  and  estimate  the  gum  in  the 
insoluble  residue  as  directed  in  §  80. 

Plalf  of  the  alcoholic  extract  may  be  evaporated  to 
dryness,  the  residue  weighed,  and  then  incinerated,  and 
the  ash  weighed ;  thus  the  total  volatile  and  non-volatile 
(organic  and  inorganic)  matter,  soluble  in  alcohol^  may  be 
estimated. 

Sugar  may  be  determined  in  the  other  half  of  the  alco- 
holic extract,  after  adding  water  and  heating  the  liquid 
on  the  water-bath  until  all  the  alcohol  is  expelled  (§  81). . 

i.  Tannic  acid. — This  acts  upon  the  cupric  solution, 
used  in  determining  sugar,  precisely  as  sugar  does,  3.7 
parts  reducing  as  much  cupric  oxide  as  5  parts  of  sugar. 
Tannic  acid  is  absorbed  when  the  wine  is  decolorized  by 
contact  with  bone-black ;  the  difference,  then,  between  the 
amount  of  cupric  solution  required  with  and  without 
treatment  with  bone-black,  will  give,  approximately,  the 
amount  of  tannic  acid.  But  in  many  cases  the  wine  would 
be  too  dark-colored  to  admit  of  a  determination  of  sugar 
by  the  cupric  solution  without  treatment  with  the  decol- 
orizing agent,  and  there  are,  moreover,  other  substances 
in  the  wine  that  are  removed  by  the  charcoal,  and  that, 
at  the  same  time,  act  on  the  cupric  solution.  When,  how- 
ever, the  determination  can  be  made,  it  answers  very 
well  for  the  comparison  of  different  wines  with  each 
other,  since  the  proportion  of  the  other  reducing  agents 
does  not  seem  to  vary  much. 

h.  Free  acids. — ^Titrate  100  grms.  of  the  wine  with  the 
standard  sodic  solution. 

Then  mix  another  portion  of  100  grms.  with  clean  sand, 
and  evaporate  it  to  dryness  on  the  water-bath,  with  con- 
stant stirring,  and  heat  it  as  long  as  any  odor  of  acetic 
acid  is  evolved  ;  dissolve  the  residue  in  water,  and  titrate 
the  solution  with  the  standard  sodic  solution.     The  dif- 


§  142.     WINE.  281 

ference  between  the  amounts  of  sodic  solution  required  in 
the  two  trials  represents  the  acetic  acid. 

Estimate  0.06  grm.  of  acetic  acid,  HC^HgO^,  for  every 
cubic  centimetre  of  this  difference,  and  0.075  grm.  of  tar- 
taric acid,  H^C^H^Og,  for  every  cubic  centimetre  of  the 
sodic  solution  required  after  the  acetic  acid  was  expelled. 

Griffin  {Chemical  Testing  of  Wines  and  Spirits)  deter- 
mined the  free  acid  as  follows,  with  a  ^  1^^  atomic  solution 
of  ammonia  for  the  standard  solution,  and  an  extract  of 
logwood  for  the  coloring  matter. 

Take  two  portions  of  wine,  of  7.5  c.c.  each,  and  add  to 
each,  if  it  is  a  white  wine,  125  c.c.  of  water,  or,  if  it  is  a 
red  wine,  250  c.c,  or  more,  according  to  the  depth  of  the 
color ;  then  add  exactly  the  same  quantity  of  the  extract 
of  log\yood  to  each  portion,  which  gives  a  color  to  the 
wine  very  much  like  that  obtained  by  painting  j^aper 
with  raw  sienna;  add  the  alkaline  solution  from  the 
burette  to  one  portion,  keeping  the  other  at  hand  for 
comparison,  with  constant  stirring ;  when  the  color  sud- 
denly changes  to  a  reddish-brown,  like  that  obtained  by 
hurnt  sienna  on  paper,  the  point  of  saturation  is  reached. 
Now,  repeat  the  experiment  with  the  other  portion  of  the 
wine,  adding  all  but  2-3  c.c.  of  the  required  quantity  of 
standard  ammonic  solution  at  once,  and  then  drop  by 
drop,  until  the  acid  is  saturated. 

Each  cubic  centimetre  of  the  alkaline  solution  required 
corresponds  to  0.1  of  an  equivalent  of  free  acid,  or,  if  we 
call  it  all  tartaric  acid,  as  it  is,  mostly,  0.0075  grm ;  and 
in  this  case  the  number  of  cubic  centimetres  used  gives 
at  once  the  number  of  grammes  of  acid  (tartaric)  in  the 
litre  of  wine. 

Good  wines  contain  4-6  grms.  of  free  acid  in  the  litre 
(300-400  grains  of  crystallized  tartaric  acid,  Griffin).  In 
poor  wine  years,  the  proportion  of  free  acid  often  rises 
as  high  as  10-12  grms.  in  the  litre. 

I  Tartar.— Add  40  c.c.  of  90"!    alcohol  to  20  c.c.  of 


282  §    142.       BEVERAGES. 

the  wine,  let  the  mixture  stand  several  days  in  a  well- 
closed  bottle,  and  then  titrate  30  c.c.  of  the  clear  liquid 
with  the  standard  sodic  solution ;  subtract  0.3  c.c.  from 
the  amount  of  soda  required,  and  then  subtract  this  re- 
mainder from  the  amount  that  would  be  required,  as  in 
Jc^  to  neutralize  the  total  free  acid  in  10  c.c.  of  wine ;  this 
second  remainder  represents  the  quantity  of  acid  that  was 
removed  from  the  wine  by  treatment  with  alcohol ;  for 
each  cubic  centimetre  of  this  remainder  calculate  0.1881 
grm.  of  tartar. 

Griffin  estimated  tartar  by  evaporatmg  100-200  c.c.  of 
the  wine  to  dryness,  incinerating  the  residue,  determining 
potassic  carbonate  in  the  ash  with  the  aid  of  the  standard 
acid,  and  allowing  one  equivalent  of  tartar  for  every 
equivalent  of  potassic  carbonate  thus  found  in  the  ash. 

He  estimated  it  also  by  adding  25  c.c.  of  alcohol  and 
as  much  ether  to  10  c.c.  of  wine,  letting  the  mixture 
stand  24  hours,  collecting  the  precipitate  on  a  dried  and 
weighed  filter,  drying  it  at  100°  C,  and  weighing  it ; 
all  but  about  0.002  grm.  of  the  tartar  will  be  precipitated 
in  this  way. 

m.  Total  tartaric  acid. — ^Evaporate  100  c.c.  of  the  wine 
to  about  half  its  volume,  precipitate  the  acid  by  lime- 
water  in  slight  excess,  filter  the  precipitate  out,  boil  it 
with  a  solution  of  potassic  carbonate,  filter  the  liquid, 
evaporate  the  filtrate  somewhat,  acidify  it  with  acetic  acid, 
precipitate  the  potassic  tartrate  with  considerable  alcohol, 
and  collect  and  treat  the  precipitate  as  directed  in  §  71. 

n.  Malic  acid. — This  is  contained  in  the  filtrate  from 
the  calcic  tartrate  in  m.  To  determine  it,  evaporate  this 
filtrate  down  to  one-third,  and  j^recipitate  the  calcic  malato 
with  alcohol,  as  directed  in  §  73.  As  this  precipitate  will 
contain  also  the  sulphuric  acid,  if  any  is  present  in  the 
wine  examined,  a  determination  of  this  acid  should  be 
made  in  a  portion  of  the  wine,  in  the  usual  manner ;  then 
estimate  the  amount  of  calcic  sulphate,  CaSO^,  2Iifi,  in 


§  142.     WINE.  283 

the  precipitate  obtained  as  above  with  alcohol ;  the  re- 
mainder, after  subtracting  this,  may  be  reckoned  as  calcic 
malate,  although  it  may  contain  a  little  succinate. 

The  acetic  acid,  malic  acid,  and  tartar,  taken  together, 
correspond  very  nearly  to  the  amount  of  soda  used  in  Ic^ 
to  determine  the  free  acid,  each  equivalent  of  tartar  neu- 
tralizing one  equivalent  of  soda. 

0,  Free  snlphuric  acid,  if  present  in  the  wine  under 
examination,  may  be  detected  and  determined  in  the  same 
manner  as  directed  in  §  138,  h. 

p.  Total  alkalies* — These  may  be  estimated  in  the  ash 
obtained  in  c,  or  in  the  following  manner. 

To  the  remaining  30  c.c.  of  the  filtrate  from  the  pre- 
cipitate by  alcohol  in  /,  add  5  c.c.  of  an  alcoholic  solution 
of  tartaric  acid,  whose  strength  is  accurately  known,  let 
the  mixture  stand  several  days,  and  titrate  25  c.c.  of  the 
clear  supernatant  liquid  with  the  standard  sodic  solution ; 
the  rest  of  the  j^otassa,  not  precipitated  in  ^,  and  the  soda, 
have  crystallized  out,  with  an  equivalent  quantity  of  the 
tartaric  acid  that  was  added;  this  quantity  of  acid  will  be 
represented  by  the  difference  between  the  amount  of  sodic 
solution  used  in  this  trial,  and  that  which  would  be  re- 
quired to  neutralize  the  free  acid  already  in  the  solution 
(see  I),  plus  the  5  c.c.  of  tartaric  acid  added.  For  each  2 
c.c.  of  this  difference  estimate  0.0471  grm.  of  potassa  and 
add  it  to  the  amount  in  the  tartar  obtained  in  /. 

The  average  composition  of  v/ine,  according  to  Nessler, 
who  examined  a  large  number  of  European  wines,  is  as 
follows:  Alcohol,  7- 10°  |„;  Sugar,  0.1  _  0.2°  |„;  Free  acid, 
estimated  as  tartaric,  0.4  -  0.8°|  ^ ;  Malic  acid,  0  -  0.3°  |„ ; 
Acetic  acid,  0-0.3°|^;  Tannic  acid,  0.02  -  0.05°|,. 
Total  dry  substance  in  solution,  1.5  —  2°|q. 


284 


TABLES. 


TABLE  I. 

THE  METRIC  SYSTEM   OF   WEIGHTS   AND    MEASURES. 

1. 

Measures  of  Length. 

1  Metre  =    1 Metre. 

1  Decimetre    =    0.1    " 

1  Centimetre  =    O.Ol  " 

1  Millimetre    =    0.001 " 

1  Metre  =  39.37 Inches. 

1  Centimetre   =    0.3937 Inch. 

1  Foot  =  30.48 Centimetres. 

1  Inch  =  25.4 Millimetres. 

The  accompanyinjr  scales,  copied  from  Professor 
H.  A.  Newton's  little  pamphlet  (The  Metric 
System  of  Weiuhts  and  Measures,  with  Tables. 
Prepared  for  the  Smithsonian  Institution),  ex- 
hibit the  relative  maj^nitude  of  the  divisions  of 
the  metre  and  inches. 

2. 

Measures  of  Volume. 


1  Cubic  metre 
1  Cubic  decimetre 
1  Cubic  centimetre 
1  Cubic  centimetre 
1  Litre 

1  Gallon  (imperial) 
1  Gallon  (wine) 
1  Hectolitre 


1000 Litres. 

1.  Litre. 

0.001     Litre. 

0.06103 Cubic  Inch. 

0.880(56 Quart. 

4.5435 Litres. 

3.79      Litres. 

2.84      Bushels. 

3. 


The  Weights  of  the  Metric  System. 


1  Kilogramme 
1  Hectogramme 
1  Decagramme 
1  Gramme 
1  Decigramme 
1  Centigramme 
1  Milligramme 
1  Kilogramme 
1  Gramme 
1 

1  Pound 
1  Ounce 
1  Grain 


1000. 
100. 

Grammes. 

10. 

(( 

L 

Gramme. 

0.1       

0.01     " 

0.001   " 

2.2046. P'ds  (avoirdupois.) 
"^■^-"■.  Ounce  " 


0.035 
15.43 
453.6 
28.3 
64.8 


—  Grains. 
.Grammes. 


.Milligrammes. 




_ 

^ 

* 







— ' 

rrz 

— < 

__^ 

:= 

— 

■ — 

^ 



— 

— ■ 

— 

= 

— 

~  • 

__ 

— 

— ■ 

_     — 

~ 

— 

- 

" 

CP      

— 

— 

t-»     — 

5     — 

t^ 

Abbreviations. 

Centimetre .• 

Millimetre 

Cubic  centimetre 

Kilogramme 

Gramme 

Milligramme 


.Cm. 
Mm. 
.C.c. 


.Kilo. 
Grm. 
.Mgr. 


TABLES. 


285 


TABLE  II. 


THE  ATOMIC  WEIGHTS  OF  THE   ELEMENTS  CONCERNED  IN 
THE  QUANTITATIVE  PROCESSES  DESCRIBED  IN  THIS  BOOK. 


Aluminium,  AI 27.5 

Barium,  Ba 137.0 

Calcium,  Ca 40.0 

Carbon,  C 12.0 

Chlorine,  CI 35.5 

Copper,  Cu 63.5 

Iron,  Fe 56.0 

Magnesium,  Mg 24.0 

Manganese,  Mu 55.0 


Nitrogen,  N 14.0 

Oxygen,  0 16.0 

Phosphorus,  P 31.0 

Platinum,  Pt 197.1 

Potassium,  K 39.1 

Silicon,  Si 28.0 

Silver,  Ag 108.0 

Sodium,  Na 23.0 

Sulphur,  S 33.0 


TABLE  III. 


FACTORS  FOR  ESTIMATING  THE  SUBSTANCE  SOUGHT 
FROM  THE  COMPOUND  OBTAINED. 


Compound 
obtained. 

Formula. 

Substance  sought. 

Formula. 

Factor. 

Al,03 
NH3 

(NH4),PtCl6 

(NH4)2PtCla 

(NH4)2PtCl6 

AgCl 

AgS 

BaSOi 

(( 
CaCOa 

u 
u 
CaC4H406 

CaS04 
COa 

u 
u 

Clay        

AI2O3,  2Si02 
2H2O 

N 

NH3 
(NH4)20 

S 
SO3 

s 

Ca 

CaO 

CaS04,2H20 

H2C4H4O5 

C4H4O4 

CaO 

CaCOs 

CaHaOa 

Ammonia 

Ammonio -platin- 

Nitrogen 

3.5150 
0.8335 

0  0763 

Ammonio  -platin- 
ic  chloride 

Ammonio  -platiu- 
ic  chloride 

Argentic  chloride 

Argentic  sulphide 

Baric  sulphate... 

u               u 

Ammonic  oxide. 

Nitrogen 

Chlorine 

Sulphur 

0.1165 

0.0638 
0.3474 
0.1481 

Sulphuricanhy- ) 

dride \ 

Sulphur 

0.3433 
0.1373 

Calcic  carbonate. 

Calcium 

Calcic        oxide ) 

(lime) \ 

Calcic      sulphate 

(cryst.) 

0.4000 
0.5600 
1.7200 

Calcic  malate 

Calcic  sulphate.. 
Carbonic  acid 

u               u 

Malic  acid 

Malic  anhydride. 
Calcic        oxide  ) 

(lime) ] 

Calcic  Carbonate. 
Calcic  hydrate... 
Humus 

0.7791 
0.6744 

0.4118 
2.2730 
1.6820 
0.4703 

286 


TABLES. 


TABLE  IIL— {Continued.) 


Compound 

■ 

obtained. 

Formula. 

Substance  sought. 

Formula. 

Factor. 

Ferric  oxide 

FcaOs 

Ferrous  oxide... 

FeO 

0.9000 

U                     11 

FcaPaOg 

Iron 

Fe 
Fe 

0  7000 

Ferric  phosphate. 

Iron 

0  5298 

(( 

Phosphoric  an-  ) 
hydride [ 

P2O5 

0.4702 

Ferrous  oxide . . . 

FeO 

Ferric  oxide 

FeaOa 

1.1110 

u 

Iron 

Fe 
CoHooO., 

0  7780 

Glucose 

Saccharose 

0  9500 

u 

CJIioOs 

Starch 

C12H20O10 
HaCeHioOe 

0  9000 

Lactic  anhydride. 

Lactic  acid 

1.1110 

Maijjnesic      pyro- 

pliospliate 

Mg,V,0, 

Magnesic  oxide.. 

MgO 

0.3604 

Maji^nesic      pyro- 

Phosphoric  anhy- 

phospliate  

MgaPaOv 

dride 

P2O5 

0.6396 

Magnesic      pyro- 

Tricalcic      phos- 

phospliate  

MgaPaOj 

phate 

CaaPaOs 

1.3960 

Mangauous  mau- 

g;anic  oxide 

MuaOi 

Manganous  oxide 

MnO 

0.9301 

Mani^anous  man- 

<i;anic  oxide... , 

MusOi 

Manganic  oxide. 

MusOa 

1.0350 

Nitrogen 

N 

Ammonia 

NH3 

1.2140 

<( 

a 

Protein      com- ) 
pounds. ...... 

6.2500 

Phosphoric  anhy- 

Tricalcic      phos- 

dride  

P2O5 

phate 

C^P,03 

2  1830 

Platinum 

Pt 

Ammonia 

0.1725 

''        

u 

Potassium 

K 

0.3968 

Potassic  chloride. 

KCl 

Potassium 

K 

0.5241 

((             (( 

" 

Potassic  oxide.. . 

K2O 

0.6314 

Potassic       oxide 

Potassa  feld-      J 
spar ] 

K2O,  SSiOa, 

(potassa) 

K2O 

AI0O3,  3SiOo 

5 . 9150 

Potassic  sulphate 

K2SO4 

Potassium 

K 

0.4489 

Potassic  oxide... 

KoO 

0.5408 

Potassic  tartrate. 

KHC4H40e 

Tartaric    anliy-  ) 
dride j 

041X405 

0.7018 

Tartaric  acid 

H2C4H4O6 

0.7974 

Potassio  -  platinic 

chloride 

KaPtCle 

Potassium 

K 

0.1602 

Potassio  -  platinic 

chloride 

KaPtCle 

Potassic  oxide... 

KoO 

0.1929 

Potassio  -  platinic 

chloride 

KaPtCls 

Potassic  chloride. 

KCl 

0.3055 

Sodic  chloride... 

NaCl 

Sodium 

Na 
NaaO 

0  3932 

a               u 

Sodic  oxide 

0.5299 

Sodic  oxide  (soda) 

NaaO 

Soda  feldspar. .  ] 

NaaO,  3SiO^ 
AI2O3,  SSiOa 

8.4680 

Sodic  sulphate, . . 

NaaSO* 

Sodiwm 

Na 
NasO 

0  3239 

u          Ki 

Sodic  oxide 

0.4366 

Sulphuric     anhy- 

dride  

SO3 

H2C4H40« 

KHC4H4O. 

1.8750 
1.2540 

Tartaric  acid 

H2C4H4O8 

Tartar 

TABLES. 


287 


J^ABLE   lY. 


ESTIMATION  OF  TANNIC  ACID  IN  BARK. 


Sp.  Gr.  at 

«|oOf 

Sp.  Gr.  at 

°|oof 

Sp.  Gr.  at 

°loOf 

Sp.  Gr.  at 

°|o   of 

15°  C. 

tannic 

15°  C. 

tannic 

15°  C. 

tannic 

15°  C. 

tannic 

acid. 

acid. 

acid. 

acid. 

1.0000 

0.0 

1.0064 

1.0124 

3.1 

1.0188 

4.7 

1.0004 

0.1 

1.00S8 

1.7 

1.0128 

3.2 

1.0192 

4.8 

1.0008 

0.3 

1.0072 

1.8 

1.0132 

3.3 

1.0196 

4.9 

1.0012 

0.3 

1.0076 

1.9 

1.0136 

3.4 

1.0201 

5.0 

1.0016 

0.4 

l.OOSO 

2.0 

1.0140 

3.5 

1.0020 

0.5 

1.0084 

2.1 

1.0144 

3.6 

1.0024 

0.6 

1.0088 

2.2 

1.0148 

3.7 

1.0028 

0.7 

1.0092 

2.3 

1.0152 

3.8 

1.0032 

0.8 

1.0096 

2.4 

1.0156 

3.9 

1.0036 

0.9 

1.0100 

2.5 

1.0160 

4.0 

1.0040 

1.0 

1.0104 

2.6 

1.0164 

4.1 

1.0044 

1.1 

1.0108 

2.7 

1.0168 

4.2 

1.0048 

1.2 

1.0112 

2.8 

1.0172 

4.3 

1.0052  ■ 

1.3 

1.0116 

2.9 

1.0176 

4.4 

1.0056 

1.4 

1.0120 

3.0 

1.0180 

4.5 

1.0060 

1.5 

1.0184 

4.6 

TABLE  V. 


PROPORTION  BY  WEIGHT  OF  ABSOLUTE  ALCOHOL  IN  SPIRITS 
OF  DIFFERENT  SPECIFIC  GRAVITIES  AT  15.5°  C.    (FOWNES.) 


Sp.  Gr. 

"lo 

Sp.  Gr. 

°lo 

Sp.  Gr. 

"lo 

Sp.  Gr. 

°lo 

0.9991 

0.5 

0.9802 

13 

0.9638 

26 

0.9416 

39 

0.9981 

1 

0.9789 

14 

0.9623 

27 

0.9396 

40 

0.9965 

2 

0.9778 

15 

0.9609 

28 

0.9376 

41 

0.9947 

3 

0.9766 

16 

0.9593 

29 

0.9356 

42 

0.9930 

4 

0.9753 

17 

0.9578 

30 

0.9335 

43 

0.9914 

5 

0.9741 

18 

0.9560 

31 

0.9314 

44 

0.9898 

0 

0.9728 

19 

0.9544 

32 

0.9292 

45 

0.9884 

7 

0.9716 

20 

0.9528 

33 

0.9270 

46 

0.9869 

8 

0.9704 

21 

0.9511 

34 

0.9249 

47 

0.9855 

S 

0.9691 

22 

0.9490 

35 

0.9228 

48 

0.9841 

10 

0.9678 

23 

0.9470 

36 

0.9206 

49 

0.9828 

11 

0.9665 

24 

0.9452 

37 

0.9184 

50 

0.9815 

12 

0.9653 

25 

0.9434 

38 

288 


TABLES. 


TABLE  YI. 

ESTIMATION  OF  SUGAR  AND  TOTAL  DRY  SUBSTANCE  IN  THE 
SUGAR  BEET,  BY  THE  SPECIFIC  GRAVITY  OF  THE  BEET. 


Sp.  Gr. 

"lo 

Total 

Sp.  Gr. 

1o 

Total 

Sp.  Gr. 

u"'" 

Total 

at 

Sugar. 

dry  eub- 

at 

Sugar. 

dry  sub- 

at 

Sugar. 

dry  sub- 

18°  C. 

staiice. 

18°  C. 

stance. 

18°  C. 

stan-ce. 

1.014 

7.00 

12.0 

1.038 

11.00 

17.3 

1.060 

13.75 

20.25 

1.016 

7.50 

12.5 

1.040 

11.25 

17.6 

1.062 

14.00 

20.50 

1.018 

8.00 

13.0 

1.042 

11.50 

18.0 

1.084 

14.25 

20.75 

1.020 

8.25 

13.5 

1.044 

11.75 

18.25 

1.066 

14.50 

21.00 

1.023 

8.75 

14.0 

1.046 

12.00 

18.5 

1.068 

14.75 

21.25 

1.024 

9.00 

14.5 

1.048 

12.25 

18.75 

1.070 

15.00 

21.50 

1.026 

9.50 

15.0 

1.050 

12.50 

19.00 

1.028 

9. To 

15.5 

1.052 

12.75 

19.25 

1.030 

10.00 

16.0 

1.054 

13.00 

19.50 

1.032 

10.25 

16.3 

1.0.56 

13.2;5 

19.75 

1.034 

10.50 

16.6 

1.058 

13.50 

20.00 

1.036 

10.75 

17.0 

1 

TABLE  YIL 

ESTIMATION  OF  STARCH  AND  TOTAL   DRY    SUBSTANCE    IN 
POTATOES,  BY  THE  SPECIFIC  GRAVITY  OF  THE  TUBER. 


Sp.  Gr. 

Total 

Sp.  Gr. 

Total 

Sp.  Gr. 

Total 

at 

Starch. 

dry  Bub- 

at 

Starch. 

dry  sub- 

at 

Starch. 

dry  sub 

18°  C. 

stance. 

18°  C. 

stance. 

18°  C. 

stance. 

1.060 

9.54 

16.96 

1.082 

14.50 

22.07 

1.106 

20.13 

27.86 

1.062 

9.98 

17.41 

1.084 

14.96 

22.54 

1.108 

20.61 

28.36 

1.064 

10.42 

17.87 

1.086 

15.42 

23.02 

1.110 

21.09 

28.86 

1.066 

10.87 

18.33 

1.088 

15.88 

23.50 

1.112 

21.57 

29.35 

1.088 

11.32 

18.79  i 

1.090 

16.35 

23.98 

1.114 

22.05 

29.85 

1.070 

11.77 

19.26 

1.092 

16.81 

24.46 

1.116 

22.54 

30.35 

1.072 

12  22 

19.72 

1.094 

17.28 

24.94 

1.118 

23.03 

30.85 

1.074 

12.67 

20.18 

1.096 

17.75 

25.42 

1.120 

23.53 

31.36 

1.076 

13.12 

20.65 

1.098 

18.23 

25.91 

1.122 

24.01 

31.86 

1.078 

13.58 

21.13 

1.100 

18.70 

26.40 

1.124 

24.50 

32.36 

1.080 

14.04 

21.60 

1.102 

19.17 

26.88 

1.126 

24.99 

32.87 

1.104 

19.65 

27.37 

1.128 
1.130 

25.49 
25.99 

33.33 
33.90 

TABLE  JX. 

HARDNESS  OF  WATER. 


C.C.  of 

Hard- 

C.C. of 

Hard- 

C.C. of 

Hard- 

C.C. of 

Hard- 

soap 

ness    or 

soap 

ness    or 

soap 

ness    or 

soap 

ness    or 

solution 

Mgr. 

solution 

Mgr. 

solution 

Mirr. 

solution 

Mgr. 

used. 

CaO. 

used. 

CaO. 

used. 

CaO. 

used. 

CuO. 

3.4 

0.5 

15.1 

3.5 

26.3 

0.5 

36.7 

9.5 

5.4 

1.0 

17.0 

4.0 

28.0 

7.0 

38.4 

10.0 

7.4 

1.5 

18.9 

4.5 

29.8 

7.5 

40.1 

10.5 

9.4 

2.0 

20.8 

5.0 

31.6 

8.0 

41.8 

11.0 

11.3 

3.5 

22.6 

5.5      1 

33.3 

8.5 

43.4 

11.5 

13.2 

3.0 

24.4 

6.0      i 

35.0 

9.0 

45.0 

13.0 

TABLES. 


289 


TABLE  VIII. 

PER  CENT  OF  BUTTER  IN  MILK,  BY  VOGEL'S  OPTICAL  .MILK 

TEST. 


C.C.  of 

"In  of 

C.C.  of 

o|o  of 

!  C.C.  of 

°|oOf 

C.C.  of 

•^lo  of 

milk  re- 

butter. 

milk 

butter. 

1    milk 

butter. 

milk 

butter. 

quired. 

used. 

used. 

used. 

2.50 

9.51 

4.50 

5.38 

0.50 

3.80 

8.50 

2.96 

2.75 

8.73 

4.75 

5.13 

6.75 

3.06 

8.75 

2.88 

3.00 

7.90 

5.00 

4.87 

7.00 

3.54 

9.00 

2.80 

3.25 

7.41 

5.25 

4.66 

7.25 

3.43 

9.25 

2.73 

3.50 

G.80 

5.50 

4.45 

7.50 

8.33 

9.50 

2.67 

3.75 

0.44 

5.75 

4.26 

7.75 

3.22 

9.75 

2.61 

4.00 

0.03     1 

0.00 

4.09 

8.00 

3.13 

4.25 

5.70     ! 

6.25 

3.94 

8.25 

3.04 

TABLE     X. 

COMPOSITION   OF    AGRICULTURAL    MATERIALS   AND   PROD- 
UCTS   IN    1000    PARTS    OF    THE    SUBSTANCE. 


From  this  Table  the  student  may  gain  some  idea  of  the 
chemical  composition  of  the  m.ore  important  substances 
relating  to  agriculture ;  although  since  this  composition 
varies  so.  widely  with  varying  circumstances,  no  great 
degree  of  precision  can  be  claimed  for  statements  of  so 
general  character,  with  whatever  care  they  may  be  pre- 
2>ared. 

The  extreme  and  the  average  composition  are  given ; 
the  latter  is  to  be  taken,  however,  as  indicating  not  the 
real  mean  of  all  the  reliable  analyses  of  the  substance 
that  have  been  made,  but  rather  as  an  approximation  to 
the  proportion  of  each  clement  or  compound  that  is  gen- 
erally found  in  the  substance  ;  in  some  cases  the  propor- 
tion of  a  component  ranged  too  evenly  from  one  limit  to 
the  other  of  the  extremes  to  admit  of  estimating  any 
iaverage  of  this  kind.  Fuller  details  may  in  some  cases 
bo  found  in  the  admirably  arranged  tables  at  the  end  of 
Prof.  Johnson'r;  "  IIow  Crops  Grow." 
13 


290 


TABLES. 
TABLE    X. 


d 

Il 

d 

d 

i 

i 

ft 

d 
6 

& 
S 

i 

< 

i 

O 

02 

Ashes,  coal 
(anthracite). 

22. 

87. 

14. 
57. 

23. 

2. 
30. 

350. 
430. 

52. 
130 

437. 
545. 

50.* 

15. 

380. 

80. 

500. 

Ashes,  coal 
(bituminous). 

15. 
147. 

0 
25. 

0 
23. 

10. 
230. 

30. 

7. 
14. 

10. 

225. 
350. 

23. 

258. 

269. 
624. 

70.* 

1     293. 

60. 

481. 

Ashes,  peat. 

20. 
220. 

0 

200. 

U 
95. 

10. 

580. 

200. 

0 
160. 

10. 
170. 

0 

730. 

10. 
7C0. 

70.* 

8. 

4. 

20. 

30. 

Ashes,  wood. 

2.* 

28. 

28. 
220. 

115. 

20. 
160. 

75 

0 
15. 

270. 
500. 

16. 
245. 

70. 

6. 

80. 

5. 

60. 

380. 

29. 

32. 

Bone  ash. 

0 
2.5 

0.3 

510. 
550. 

8. 
14. 

530. 

10.6 
5. 
9. 

8.5 

5.— 10. 

Bone-black. 

30. 
40. 

58. 
880. 

"soo" 

t 

t 

275. 
430. 

42. 
52. 

400. 

7. 

50. 

Bone  meal. 

47. 
167. 

520. 
680. 

^ 

t 

260. 
360. 

11.0 
0.7 

5. 

2.8 
15.5 

75. 

600. 

325 

10. 

Cement     (hy- 
draulic). 

1. 

11.3. 

7. 

0 
17. 

550. 
628. 

602. 

0 
22. 

53. 
94. 

4.5. 

61. 

.229. 
260. 

6.3 

10.4 

73. 

33. 

240. 

Cheese. 

95. 
520. 

5. 
67. 

6.(?) 

7. 

380. 

43. 

2.5 

38. 

0.3 

0.1 

Clay. 

0 
330. 

130. 

0 
33. 

19. 

0 

27. 

9. 

0 
183. 

0 
40. 

100. 
390. 

0 
230. 

150. 
770. 

20. 

10. 

280. 

90. 

480. 

(3) 

20. 
100. 

"35^ 

3. 

58. 

5. 

7. 

40  1  '^ 

10. 
50. 

30. 

Coprolites. 

460. 
360. 

15. 

20.-60. 
40. 

Excrements, 
Bolid(Herbiv). 

obb. 
906. 

764. 

11. 

58.7 

0.77 
4.8 

I).  26 
1.9 

0.009 
0.08 

1.4 
10.7 

4.6 

1. 
3. 

2.5 

0.43 
1.4. 

16. 
29.4 

25. 

3. 

0.9 

0.05 

1.0 

21. 

Excrements, 
Bolid     (Man). 

708. 
S30. 

22. 
34. 

2.5 

1.4 
i. 

1.67 

0.18 
1.2 

0.6 

5.8 
7.2 

2.9 
3.6 

0.6. 

1.9 
2.4 

SOO. 

28. 

6.4 

3.2 

2.1 

In  1000  parts  of  the  fuel.— t  Possibly  present. 
33;    KnO  and  NaaO  usually  0.— (2)    Mn,  0—0.3; 
Fluorine,  0—50 ;  average  30. 


— (1)  Fluorine. 36  — 40,  average 
K2O  and  Na^O  mostly  0.— (3) 


TABLES. 

TABLE    IL.— [Continued. 


291 


i 

6 

6 

■  o 

02 

d 

125 

iilM 

i 

Ashes,  coal    (an- 
thracite), 

1 

0 
tr. 

Ashes,  coal 
(bituminous). 

u. 

84. 

0. 
66. 

50. 

10. 

Ashes,  peat. 

0. 
370. 

0. 

80. 

0 
306. 

0 
65. 

50. 

30. 

10. 

Ashes,  wood. 

7.8 
57. 

18. 
48. 

t 

4. 

50. 

Bone  ash. 

tr. 

380. 
400. 

390. 

14. 

40. 

30. 

Bone-black. 

40. 

100. 
380. 

300. 

15. 
27. 

5. 
32. 

7. 

17. 

Bone  meal. 

180. 
280. 

do. 

:28. 
50. 

38. 

t 

1 

220. 

1 

Cement     (.hy- 
draulic). 

0. 

18.8 

10.2 

Cheese. 

11.5 

t 

t 

80. 
440. 

240. 

lOJ. 
tiOO. 

310. 

Clay. 

Coprolites. 

7.<) 
10.6 

9.0 

30. 
380. 

1. 
67. 

traces 

0 
25. 

230. 

30. 

Excrements, 
solid    (Herbiv). 

0.47 

1.58 

2.2 
5.5 

t 

t 

2.2 

9.0 

17. 
23. 

86. 
110. 

80. 
110.. 

10. 
13. 

0.87 

3.6 

4.7 

20. 

95. 

95. 

10. 

Excrements, 
solid    (Man). 

0.3 

o.y 

8.5 
10.9 

t 

t 

4. 

t 

t 

t    ' 

t 

0.6. 

9.9 

1 

t  Present.— T^  Possibly  present. 


292 


TABLES. 

TABLE    X.—lC'oniinued. 


M 

d 

d 

s 

d 

i 

< 

g 

Flesh. 

446. 
590. 

10. 
37. 

4.1 
5.2 

0 

1. 

0.2 
0.8 

0.2 
0.5 

0.4 

0.1 
0.3 

524. 

22. 

4.5 

0.7 

1  0.3 

0.2 

Fodder,  dry, 
graminacese. 

118. 
180. 

24. 
111. 

? 

0.13 
0.4 

150. 

66. 

17.1   i  4.7 

7.7 

3.3 

0.2 

19.7 

Fodder,  dry, 
legumiuosffi. 

110. 
200. 

45. 

80. 

10.6 
19.5 

0 
4.7 

1 

15. 
31. 

19. 

2.6 
7.0 

5.0 

0.3 
1.7 

0.0 
2.'7 

160. 

70. 

15.8 

1.5 

0.36 

1.5 

Fodder,:,'reen, 
graminaccse. 

090. 
870. 

7. 
21. 

5.3 
11.6 

0.1 
1.6 

1 

0.7 

2.7 

0.3 
1.9 

t 

2.1 
12.3 

745. 

18. 

7. 

0.5 

1.5 

0.7 

7.3 

Fodder,  <,n-eeii, 
legnmiuosse. 

740. 
850. 

10. 
20. 

1.0 
6.6 

0 
1.1 

0 
2.G    * 

3.0 

8.5 

0.6 
1.6 

t 

0.1 
O.G 

804. 

12. 

1.5 

0.4 

4.9 

1.0 

0.4 

(1) 
Fruits. 

760. 

880. 

2. 
9. 

1.0 
2.4 

0 
0.7 

1 

i 

0.1 
0.4 

0.2 

0.08 
0.33 

820. 

4. 

2.0 

0.3 

0.3 

0.19 

Guano, 

100. 
200. 

330. 
400. 

16.0 
30.0 

12. 

62. 
100. 

140. 

344. 

20.0 

35. 

12. 

8. 

12. 

Gnano, 
phosphatic. 

10. 
140. 

100. 

780. 
950. 

0 
12.0 

0 

39. 

498. 

TqoT 

0 
21. 

4. 

89. 

0 
54. 

0 
13. 

890. 

2.5 

6. 

2. 

3.7 

Gypsum. 

188. 
205. 

197. 

• 

■293. 
325. 

309. 

tr. 

tr. 
.50. 

8. 

21. 

0.03 
1.12 

0 

0.7 

410. 
550. 

3.4 
15.0 

1.7 
10. 

2.  -40. 

0.2 

500. 

8. 

660. 
710. 

34. 

78. 

1.2 
12.0 

0.2 

2.8 

2. 
15. 

0.5 
1.7 

7.5 
18.0 

farm-yard. 

1.7-  8. 

680. 

58. 

8.0 

1.2 

11. 

1.0 

3. 

14.0 

750. 
790. 

70. 
73. 

sT 

O.G 
0.8 

0.7 

10. 
19. 

1.8 
3.8 

17. 
23. 

farm-yard. 

770. 

72. 

15 

1.6 

6.7 

22. 

Han.           ''^ 

13. 
100. 

30. 

tr. 
14.8 

1.0 

Ir. 
15. 

0 
0.99 

2. 

520. 

3. 
220. 

^ 

30.-90. 

50 

♦  In  the  dry  substance,  t  Present.  1  Possibly  present.  (1)  Free  acid,  esti- 
mated as  malic  acid,  1.0—20.0;  averasje  8.6.— (2)  Oxalic  acid,  58—80 ;  averajjc  60. 
ITric  acid  present.— (3)  Fluorine,  traces.  Sand  8— 47— (4)  Insoluble  silicates 
and  sand,  50—850. 


TABLES. 


293 


TABLE 

X.—[C'onimued. 

i 

O 

i 

02 

O 

^ 

11 

III 

Flesh. 

0 
0.4 

4.3 

5.8 

t 

0.1 

0.7 

t 

123. 
174. 

144. 

210. 
397. 

5.0 

0.4 

299. 

Fodder,  dry, 
•jraminaceae. 

3.3 

T 

1.7 
3.3 

t 

30. 
180. 

170. 
400. 

225. 
514. 

12. 
56. 

3.4 

4.1 

2.5 

5.3 

90.  260. 

410. 

28. 

Fodder,  dry, 
leguminosse. 

1.5 
5.3 

2.8 

4.7 
9.0 

u 

0.031 

0.9 
2.7 

1.3 
2.1 

t 

72. 
190. 

140. 

190. 
400. 

280. 

150. 
480. 

12. 
55. 

6.5. 

1.8 

1.5 

330. 

30. 

Fodder,  <!;reeu, 
graminaceae. 

U.2 
1.2 

1.3 
2.4 

tr. 

0.3 

0.8 

0.5 

0.4 
1.9 

1.0 

t 

17. 

60. 

30. 
170. 

35. 
230. 

3. 
15. 

0.7 

1.7 

30. 

90. 

129. 

10. 

Fodder,  green, 
leguminosae. 

0.2 
2.2 

0.9 
2.0 

0.007 
5.0 

0.3 

0.8 

0.2 
1.0 

t 

22. 
72. 

30. 
160. 

50. 
140. 

4. 

9. 

0.8 

1.4 

0.5 

0.4 

28. 

60. 

75. 

6. 

Fruits. 

0.4 
0.7 

0.5 

0.1 
0.4 

t 

3.2 

8.0 

s^o" 

28. 
117. 

49. 

14. 
120. 

* 

64. 

0.2 

0.1 

0.2 

Guano, 
ammoniacal. 

60. 
137. 

80. 
170. 

110. 

7. 

100. 

Guuuo, 
phosphatic. 

0 
•270. 

170. 
420. 

0 
5. 

0 
15. 

0 

8. 

tr. 
40. 

G. 

340. 

3.2 

1.5 

Gypsum. 

il8. 
160. 

tr. 
30. 

140. 

Limestone. 

0.;^ 

G.7 

0.03 
12.0 

310. 
140. 

0.32 
1.76 

0 
1.6 

2.0 

0.8 

too. 

Manure,  fresii 
farm-yard. 

1.0 
3.0 

12 
3.0 

t 

0.6 
2.0 

0.8 

4.0 
7.4 

6.0 

t 

+ 

t 

t 

2.0 

2.8 

• 

Manure,  rotted 
farm-yard. 

1.2 
2.4 

"iTs" 

3.4 
4.5 

t 

0.2 
1.6 

6.0 

3.9 

0.9 

Marl. 

tr. 
15. 

Ir. 
5. 

30. 
450. 

tr. 

*  Sugar.— t  Present.^l  Possibly  present. 


294 


TABLES. 


TABLE 

X.-[Cmlinued. 

d 

^< 

d 

d 

i 

^ 

d 

< 

o 

Milk. 

8G0. 

875. 

7. 
8.5 

~0~ 

0.2 

870. 

7.3 

1.7 

1.5 

(1) 
Phosphorite 
(Apatite). 

4. 
25. 

0 
12.6 

0 
5.0 

200. 
550. 

0 
2.3 

1.8 

. 

0 
66. 

0.37—90. 

15. 

5.6 

3.0 

440. 

50. 

Plants,  cereal; 
grain. 

126. 
148. 

7. 
39. 

3.3 
5.5 

4.6 

0.2 
1.0 

0.5 

tr. 
3.4 

0.14 
10. 

1.8 
2.2 

0 
0.6 

0.3 
12'. 

142. 

20 

0.6 

1.9 

0.18 

Plants,  cereal: 
straw. 

90. 
225. 

40. 
5G 

4.9 
16.6 

0 
3.5 

tr. 
1.5 

2.3 
5.0 

0.4 
2.6 

.02 
2.11 

18. 

150. 

45. 

6.0 

2.5 

3.6 

1.4 

1.0 

25. 

Plants,  com- 
mercial. 
(Hops,  tobac- 
co, etc.) 

100. 
300. 

28. 
198 

5.2 
54.1 

0.9 
7.3 

5. 
73. 

8. 

2.0 
20.7 

.08 
3.0 

0.8 
19. 

220. 

.50. 

15.0 

1.6 

3.0 

1.74 

Plants, 
Icc^iimc ; 
seeds. 

128. 
148. 

17. 
35. 

6.3 
12.0 

0.4 
6.0 

0.6 
2.7 

0.4 
2.1 

0. 
0.48 

0.2 
0.4 

144. 

25. 

9.8 

1.0 

1.5 

1.7 

0.15 

0.3 

Plants, 
le,i,'ume ; 

100. 
190. 

150 

lis. 
584. 

50. 

9.7 
25.9 

18.9 

1.1 
3.9 

2.6 

9.5 
25. 

1.9 
4.6 

0.09 
0.2 

2.4 
3.1 

15. 

3.0 

0.13 

2.7 

Potatoes ; 
tubers. 

150. 
800. 

775. 

5.6 
46. 

10. 

5.6 
6.7 

6.1 

0.1 
0.4 

0.2 
0.4 

0.25 

0.3 
0.4 

0.04 
0.06 

0.05 

0.2 

0.25 

0.35 

Potatoes ; 
tops. 

770 
320. 

11. 
16. 

0.7 
2.3 

t 

5.1 
5.5 

5.3 

2.6 
2.7 

2.65 

0.5 

8.5 

797. 

14. 

1.5 

0.21 

Root-crops ; 
roots. 

754. 

920. 

6. 
10. 

1.9 

4.3 

0.8 
2.0 

0.4 
0.9 

0.7 

0.1 
0.7 

0.4 

0.01 
0.29 

0.1 
0.3 

875. 

8. 

3.5 

1.0 

0.09 

0.2 

Root-cropa ; 
tops. 

7ti5 
920. 

15. 
33. 

3.2 
6.0 

0.5 
6.0 

1.7 

8.6 

0.4 
3.3 

0.15 
0.28 

0.1 
2.6 

85 

17. 

4.1 

1.5 

4.8 

1.3 

0  26 

1.0 

Salt. 

12. 
63. 

937. 
988. 

0 
2.3 

t 

890. 
i)94. 

975. 

1.15 
9.7 

0.2 

2.8 

0 

tr. 

0 
tr. 

53.0 

34. 

963. 

2.2 

8.0 

1.7 

Saltpetre 
(Chili). 

1. 
20. 

t 

330. 
358. 

340. 

1.0 

• 

10. 

980. 

1.0 

29.0 

t  Present.— 1  Possibly  present.— (1)  Fluorine  0—49 ;  averase  28.— (2)  NaOg, 
usually  0. 


TABLES. 


295 


TABLE    X.—lConiinued. 


i 

0 

s' 

m 

5 

^ 

2  a! 

11 

Id 

Ill 

1 

Milk._ 

0.7 

24. 

68. 

38. 

29. 
83. 

47.* 

22. 

60. 

0.1 

1.9 

35. 

Pliosphorite. 
(Apatite). 

tr. 

300.0 
400.0 

360.0 

3.0 
43.0 

0. 
5.0 

25.0 

Plants,  cereal ; 
grain. 

0.1 
0.5 

5.5 
10.0 

tr. 

6.8 

0.4 
1.7 

0.18 
0.27 

19. 

42.5 

526. 
270. 

7. 
165. 

500. 
765. 

5. 

70. 

0.3(5 

8.0 

1.0 

0.2 

20.0 

120. 

60. 

640. 

Plants,  cereal ; 
straw. 

0.9 
2.5 

1.4 
3.8 

0 
5.2 

0.9 
4.0 

1.2 
1.3 

1.7 
4.2 

6. 
100. 

290. 
550. 

180. 
455. 

300. 

6. 
25. 

1.4 

2.5 

2.0 

3.0 

37. 

460. 

13. 

Plants,  commer- 
cial.   (Hops,  to- 
bacco, etc.) 

0.8 

T.7 

3.3 
9.0 

t 

0 
4.8 

3.4 

0.7 
8.8 

t 

55. 

48 

2.0 

7.1 

672. 

Plants,  legume ; 
seeds. 

0 
2.3 

5.2 
8.1 

0 

tr. 

0 
2.5 

0.2 
0.6 

t 

200. 
350. 

37. 

145. 

270. 
600. 

12. 
76. 

1.3 

8.0 

2.4 

0.5 

250. 

97. 

400. 

32. 

Plants,  legume ; 
straw. 

0.1 

2.8 

2.7 
6.1 

t 

0.7 
2.2 

2.7 

8.1 

5. 

IS. 

48. 
100. 

250. 
530. 

170. 
400. 

10. 
50. 

2.0 

3.8 

1.5 

4.5 

9. 

80. 

390. 

300. 

18, 

Potatoes;  tubers. 

0.3 
0.6 

1.6 
2.0 

1 

0.2 
0.94 

0.9 

t 

0.8 
3.0 

5. 
40. 

3. 
27. 

120. 
160. 

0.5 
8.0 

0.45 

1.7 

2.0 

18. 

10. 

190. 

3.0 

Potatoes;  tops. 

O.G 
0.9 

0.6 
1.0 

0.78 

0.5 
0.0 

0.4 
0.7 

+ 

t 

t 

t 

0.75 

0.8 

0.55 

0.55 

5.5 

Koot-crops : 
roots. 

0.3 
1.1 

0.5 
1.4 

0.12 
3.6 

0 

4.4 

0.1 
2.5 

t 

5. 
26. 

I 

23. 
155. 

0.8 
8.0 

0.0 

1.0 

0.67 

3.9 

0.33 

11. 

12. 

85. 

1.0 

Koot-crops ; 
tops. 

1.1 
3.0 

0.8 

2.0 

^ 

0.5 
1.4 

0.3 
10. 

8. 

12. 
38. 

9. 
34. 

21. 
129. 

3. 
10. 

1.7 

1.5 

0.6 

26. 

25. 

60. 

6. 

Salt. 

1.4 
10.6 

0 

tr. 

0.5 
3.7 

1.9 

6.0 

Saltpetre 
(Chili). 

371. 

020. 

10. 

596. 

8.0 

170 

*  Sugar.— t  Present.—^  Possibly  present. 


296 


TABLES. 


TABLE 

X.— [Continued. 

i4 

d 

d 

i 

i 

i 

i 

% 

^ 

i 

1 

(t) 

Soils. 

920. 
990. 

tr. 

28. 

tr. 
20.7 

0.0023 
0.102 

tr. 
170. 

tr. 
14.0 

8 
140. 

15.  - 
110. 

t 

950. 

4.0 

2.0 

0.04a5 

5.0 

3.0 

50.  _ 

30. 

Sugar-beet. 

800. 
900. 

3. 
6. 

2.5 
3.5 

0.15 
0.3 

0.4 
0.9 

1 

0.4 
0.7 

0.5 

0.16 
0.21 

0.1 
0.2 

815. 

5. 

3.0 

0.2 

0.7 

0.2 

0.12 

0.1 

Supetphos- 
phate. 

94. 
223. 

155. 

576. 

728. 

065. 

1 

*! 

159. 
325. 

230. 

0 

0 
3.0 

' 

1.0 

(3) 
Urine. 
Herbivora. 

S(50. 
925 

17. 
47. 

6.0 
20. 

2.0 
5.0 

t 

0.31 
0.16 

875. 

SO. 

13. 

3.0 

4.2 

U,.,„e.          ''' 
Man. 

934. 
970. 

10.3 
14.5 

1.7 
5.0 

1.0 
3.0 

3.6 
8.0 

0 
0.9 

0 
0.33 

0 
0.23 

948. 

13.5 

2.5 

2.0 

6.0 

0.26 

0.2 

Water,  rain. 

0 

tr. 

0 
tr. 

0.0001 
0.004 

0 
tr. 

0 
tr. 

J 
tr. 

J 

tr. 

).0014 

(5) 
Water,  river. 

0 
0.013 

9 
0.024 

0.00009 
0.005 

0.007 
0.1 

0.002 
0.032 

0 
0.007 

0 
0.012 

0.001 
0.013 

3.001 

0.061 

0.01 

0.006 

(6) 
Water,  spring. 

0 
0.41 

0 
0.58 

0 
0.0006 

0.002 
0.23 

0 
0.104 

) 
0.0128 

) 

J. 0045 

0* 
0.14 

0.02 

traces  to  17  ;  average  0.8.  SiOj  and 
-(2)  FC2O3,  usually  traces.  Sand  and 
iblc  p2<^5  i'l  older  and  fo 


t  Present. — 1  Possibly  present. — (1)  Mn, 
insoluble  silicates  240 — 930;    average  770.- 

insoluble  silicates  29—178 ;  average  48.  Soluble  P2O5  in  older  and  foreign  phos- 
phates, 120;  in  recent  American.  &3.  Chlorine,  usually  0.— (3)  ITippuric  acid 
1.8—60.  Urea,  18—70;  average  28.— (4)  Urea.  23—33;  average  29.  Uric  acid, 
0.5-1.1;  average  1.— (5)  Mn.  0—0.003.— (6)  AI2O3,  NH3,  FcaO,,  P2O,,  and  N,0, 
usually  0.  MgO,  K^O,  Na^O,  SO3,  CO2,  and  CI,  rarely  0.  Organic  matter  0-0.07 ; 
average  0.03. 


TABLES. 


297 


TABLE    X.—iConiinued. 


O 

02 

8' 

02 

o 

^ 

i4 

3i  mU 

i 

Soils. 

O.OT 
11.0 

O.OOli  0.001 
5.00      0.12 

0 
220. 

0 
14. 

0.5 
50. 

1.5 

1.0     1  0.03 

5. 

0.3 

2. 

Sugar-beet. 

O.IS 
0.28 

0.37 
1.0 

0.3 

1.7 

t 

t 

t 

6. 

28. 

10. 
34. 

66. 
138. 

* 

6. 
9. 

0.2 

0.7 

1.0 

0.1 

8. 

13. 

100. 

8. 

Superphosphate. 

121. 
314. 

12«. 
233. 

0 
59. 

r 

210. 

170. 

20. 

Urine. 
Herbivora. 

0 
l.G 

8.7 
14.0 

10.8 

0 
3.3 

4.4 
26. 

15. 

Uriue. 
Man. 

0.4 

3.7 

1.7 
3.0 

2.0 
5.0 

7. 
18. 

1.5 

2.0 

3.6. 

14.5 

Water,  raiu. 

0 
tr. 

0. 
tr. 

0.0001 
O.OOG 

O.OOOo 

Water,  river. 

0.002 
0.0T9 

0.022 

0.001 
0.01 

0.0017 
0.08 

0.046 

0 
0.089. 

0.01 

Water,  spring. 

0 
0.5 

0 
0.006 

3 
0.67 

0 
0.970 

0 
0.560 

0.2 

*  Sugar.— t  Present. 


INDEX, 


Acetic  acid,  as  reagent,  8 — estima- 
tion, 101— in  vinegar,  2G8— oc- 
currence of,  145— reactions 101 

Acetometer 24 

Acids,  free,  in  wine 280 

Albumen,  llT-in  millc 2G3 

Albuminoids,    see     protein     com- 
pounds. 
Alcohol  as  reajjent,  10 — estimation, 

12G— in  wine 270 

Alcoholometer 24 

Alkalies,  elimination  by  milk  of 
lime,  157- by  oxalic  acid,  158 — 
estimation  as  chlorides,  53,  157 
—as  sulphates,  53— in  gypsum, 
238- in  limestone,  209— in  marl, 

207— in  wine 283 

Alumina,  hydrated,  in  soil 180 

Aluminium,  elimination  of,  153 — es- 
timation of,  G6— reactions G5 

Ammonia,  estimation  of  by  distilla- 
tion with  sodic  hydrate  and  ti- 
tration, 57— by  distillation  and 
Nessler's  solution,  58— platinic 
cliloride,  55— Schlossing's  proc- 
ess, 56— in  beets,  260- in  fodder, 
aqueous  extract  of,  254 — in  gua- 
no, 232 — in  manure  of  the 
farm-yard,  214— in  soil,  1^— in 
Buperphosphatc,  235 — in  urine, 

219— in  water 272 

Ammonia,  reactions  of. 54 

Amnionic  acetate  as  i*eagent,  car- 
bonate chloride,  fluoride,  10 — 
hydrate  molybdatc,  nitrate,  oxa- 
late,   sulpliate,    sulphide,   11— 

tartrate 12 

Ammonio-ferrous  sulphate,  as  re- 
agent   12 

Ammonium,  see  ammonia. 

Analyses,  calculation  of 42 

Analysis,  qualitative,  course  of  for 
acids,  130— for  bases,  130— table 

for ....144 

\ 


Analysis,  quanlitativc,  schemes  for, 
IGl — special  methods  for  separa- 
tion in 146 

Animal  substances,  ash  of 248 

Aqua  regia,  as  reagent '8 

Argentic  nitrate  as  reagent,  12— 
standard  solution  of 95 

Arsenic,  occurrence  of,  145 — reac- 
tions   73 

Artichokes 262 

Ash  analysis,  preparation  of  asli 
for,  241— statement  of  results. .  .247 

Ash,  elimination  of  carbon  and  car- 
bonic acid  in 150 

Ash  of  animal  substances,  248— of 
bone-black,  230— of  bone-meal, 
228— of  coal,  243— of  flour,  262— 
of  fodder,  aqueous  extract,  253 
—of  green  fodder,  251— of  fuel, 
249— of  guano,  232— of  manure 
of  the  farm-yard,  213,  21G— of 
milk,  263  —  of  peat,  243  —  of 
plants,  241— of  seeds,  2G2— of 
superphosphate,  235,  236  —  of 
urine,  218,  219— of  wine,  278— of 
wool , 270 

Asli  of  plants,  carbonic  acid,  clilo- 
rine,  243 — coal,  sand  and  silica,  243 

Ash  of  plants,  Ileichhardt's  method 
of  preparing,  for  estimation  of 
sulphur  and  chlorine 24G 

Ash  rich  in  carbonates,  243 — rich  in 
silica 244 

Ash,  sulphur  in 246 

Aslies  of  fuel,  carbonic  acid,  chlo- 
rine in,  complete  analysis  of, 
potassa  in 249 

Baker  guano 234 

Baric  acetate  as  reagent,  chloride 
hydrate,  nitrate ^ . . .  13 

Barium,  occurrence  of,  145— reac- 
tions   59 

Barlv,  tanner's,  tannic  acid,Avater  in,  270 

Beets  (and    turnips),  ammonia  In, 


INDBX. 


299 


258— ash  of,  258— crude  cellulose 
in,  fat,  258— nitric  acid  260— ni- 
trogen, pectose,  258— starch  200 
—sugar,  258— water 257 

Bone-ash 231 

Bone-black,  ash  of,  230 — calcic  hy- 
drate in,  carbonic  acid,  chlo- 
rine, nitrogen,  phosphoric  acid, 
etc.,  water 230 

Bone-meal,  ash  of,  228,  229— fat  in, 
fineness  of  division,  gelatine  in, 
229— nitrogen,  phosphoric  acid, 
water 228 

Bunsen's  method  of  filtration 33 

Butter  (and  cheese),  casein  in,  fat, 
267— salt,  208— water 267 

Butter  in  milk,  estimation  of,  204, 
266 — by  Vogel's  optical  milk- 
test •:65 

Calcic  chloride  as  reagent,  hydrate, 
fluoride,  sulphate 14 

Calcic  hydrate  in  bone-black 230 

Calcium,  elimination  of,  157— esti- 
mation of  as  carbonate  by  igni- 
tion of  oxalate,  60— as  lime  by 
ignition  of  oxalate,  61 — as  oxa- 
late by  titration  of  oxalic  acid, 
Gl — as  oxalate  in  presence  of 
phosphoric  acid,  62— as  sulphate 
by  conversion  of  oxalate  into 
sulphate,  62  —  reactions,  60  — 
separation  from  magnesium 04 

Calculation  of  analyses 42 

Carbon  eliminated  from  residue  left 
after  incineration,  150— in  urine. 223 

Carbonic  acid,  estimation  of,  79— 
by  Fresenius's  apparatus,  81 — 
in  ash  left  in  the  determination 
of  volatile  matter,  150 — in  ash 
of  plants,  24:3,  244— in  ashes  of 
fuel,  249— in  bone-black,  230— 
in  gypsum,  238— in  manure  of 
the  farm-yard,  213,215 — in  marl, 
206— in  soils,  173— in  urine,  218 
— reactions  of,  79  —  separation 
from  chlorine 83 

Casein,  118 — in  butter  and  cheese, 
267— in  milk 263,  266 

Cellulose,  lOS  —  in  excrements  of 
animals,  223— in  fodder,  252,  250 
—in  seeds,  etc.,  262 — in  roots, 
258 — reactions 108 


Cement,    hydraulic,    analysis    and 

testing  of 211 

Cheese,  (see  also  batter) 207 

Chili  saltpetre,  adulterations  detect- 
ed, 240 — complete  analysis  of, 
239— nitric  acid  in,  240— potash, 

soda,  water  in 239 

Chlorine,  estimation  of  by  gravime- 
tric process,  94— by  volumetric 
process,  95— in  ash  of  fuel,  249 
—in  ash  of  plants,  243,  244--in 
bone-black,  230  —  in  farm-yard 
manure,  215 — in  organic  combi- 
nation, 152 — in  the  plant,  245 — 
in  soil,  186— in  urine,  220— reac- 
tions   of,   94 — separation   from 

carbonic  acid 83 

Citric  acid,  as  reagent,  8 — occur- 
rence of,  145~reactions 103 

Clark'%^  method    of    determining 

hardness  of  water 274 

Clay 212 

Coal  (carbon)  in  ash  of  plants 243 

Coal  ashes 250 

Cohaltic  nitrate  as  reagent 15 

Cochineal  as  reagent 15 

Copper,  occurrence,  145 — reactions.  73 
Coprolites,  complete   analysis  of— 

phosphoric  acid  in 231 

Cupric  acetate  as  reagent,  sulphate,  15 

Curcuma-paper 15 

Cyanogen,  occurrence,  146— reac- 
tions   97 

Desiccator,  the 40 

Desiccation  of  substances 147 

Division  of  solutions  in  quantita- 
tive analysis 40 

Dragendortf' s  process  for  estimat- 
ing starch Ill 

Dung  of  animals 223 

Ether,  as  reagent 15 

Evaporation,  27— of  solutions  con- 
taining excess  of  amnionic  salts, 
when  the  residue  is  to  be  ignit- 
ed   28 

Excrements,  solid •  223 

Fat,  125— in  beets,  258— in  bone- 
meal,  229  — in  butter,  267  — in 
flour,    262— in    fodder,   252— in 

milk,  264— in  seeds 262 

Fehling's  solution 113 

Ferric  chloride  as  reagent,  15— ni- 


BOO 


INDEX. 


trate,  oxide 15 

Ferric  oxide,  elimination,  153 — esti- 
mation, GT  —  hydrated,  with 
aluminic  hydrate  in  soil,  18G — 
and  other  substances  in  farm- 
yard manure,  21G— reactions,  6G 
-—separation   from    phosphoric 

acid 153 

Ferrocyanogen,    occurrence,   14G  — 

reactions 98 

Ferrous  chloride  as  reagent,  IG— 

sulphide IG 

Ferrous  oxide  in  soil,  estimation, 

187— reactions 66 

Fertilizers,  213 — commercial,  tariff 

of  prices  for  valuation  of 226 

Fiber,  see  cellulose. 

Fibrine 118 

Filters,  incineration  of,  38 — wash- 
ing of  with  dilute  acid SI 

Filtration,  31— byBunseu's  process, 
33 — by  the  wash-bottle  arrange- 
ment   37 

Fleck's    method    of    determining 

hardness  of  water 276 

Flour,  (see  also  seeds) 262 

Fluorine,  reactions 09 

Fodder,  aqueous  extract  of,  estima- 
tion, 253— ammonia  in,  254— -ash 
of,  253— gum,  nitric  acid  in,  255 

—nitrogen,  254— sugar 255 

Fodder,  dried,  251— ash,  251~ccllu- 
lose  in,  fat,  protein  compounds, 

253— starch,  257— water 251 

Fodder,  green,  ash  of,  water  in, 
preparation  of  sample  for  analy- 
sis  251 

Gelatine  in  bone-meal 229 

Glucose,  estimation,  reactions 113 

Graduated  instruments,  testing  and 

use  of 40 

Guano,  amraoniacal  (Peruvian),  ash 
of,  and  ammonia  in,  232 — com- 
plete analysis  of,  233 — marks  of 
a  good  article,  233— nitrogen  in, 
232— oxalic  acid,  233— phosphor- 
ic acid,  etc.,  232 — solubility  in 
water,  233— uric  acid  in,  233— 

Avater  in 232 

Guano,  phosphatic  (Baker,  etc.) 234 

Gum,  estimation  of,  112— in  fodder, 
aqueous    extract    of,    255  —  in 


wine ......279 

Gypsum,  alkalies  in,  and  carbonic 
acid,  238— complete  analysis  of, 
237— solubility   in    acid,  water 

in 237 

Heat,  absorbent  power  of  soil  for, 
and  c<mducting  power,  197— re- 
taining power 193 

Ilippuiic  acid,  estimation,  reac- 
tions, separation  from  iiric,  106 

— in  urine. , 221 

Hops,  statement  of  analysis  of  ash 

of 248 

Ilumus  in  marl,  208— in  soil 1'83 

Ilydric  disodic  phosphate  as  re- 
agent , 21 

Ilydriodic  acid,  reactions  of 98 

Hydrochloric  acid  as  reagent,  8— es- 
timation, sec  chlorine  —  reac- 
tions   94 

Hydrocyanic  acid 97 

Hydroferrocyanic  acid 98 

Hydrofluoric  acid 99 

Hydrogen  as  reagent,  16— in  urine,  223 
Hydrosulphuric  acid  as  reagent,  8— 
estimation,  sec    sulphur— reac- 
tions   98 

Hygroscopic  moisture,  estimation.. 147 
Ignition  of  precipitates,  38 — of  resi- 
dues containing  excess  of  am- 
nionic salts 28 

Incineration  of  filters,  SB—to  deter- 
mine organic  matter 149 

Indigo  solution  as  reagent 16 

Iodine  as  reagent,  16 — occurrence, 

146— reactions 98 

Iron  (see  also  ferric  oxide),  estima- 
tion by  precipitation,  67  —  by 
volumetric  process  with  potas- 
sic  permanganate,  G7— by  volu- 
metric process  witli  sodic  hypo- 
sulphite, 70  —  reactions,  06  — 
separation    from    alumina  and 

phosphoric  acid 153 

Iron  turnings  as  reagent,  16 — wire..  16 
Lactic  acid,  estimation,  105 — occur- 
rence, 145 — reactions 104 

Lactometer   24 

Lacto-protein  in  milk 266 

Lactose,  117— in  milk 260 

Lead,  occurrence,  146 — reactions..-.  72 
Lead-paper  as  reagent 16 


INDEX. 


501 


Levigation 2G 

Lovulose 115 

Lime,  burned 2C9 

Lime  in  marl,  20G— in  water,  27:3 — 
reactions   and   estimation,  see 

calcium 

Limestone,  209— alkalies  in,  209— 
value  for  mortar  lime,  210— for 

hydraulic  cement 211 

Litmus-paper,  blue  and  red IG. 

Maijnesia  (calcined)  as  reagent,  17 

—magnesia  mixture 17 

Magnesium,  elimination  from  mix- 
ture of  metals,  etc.,  157 — esti- 
mation as  pyrophosphate,  GS— 
reactions,  G2— separation  from 
calcium  as  pyrophosphate,  04 — 

by  sulphuric  acid G5 

Malic  acid,  estimation,  104  —  in 
wine,  282 — occurrence,  145— rc- 

aclions 104 

Malt,  as  reagent 17 

Manganese,  elimination  from  mix- 
ture of  substances,  150 — estima- 
tion, 71— occurrence,  146— reac- 
tions   71 

Manganic  binoxide  as  reagent 17 

Manures,  commercial,  general  con- 
siderations, 224  — nitrogen  in, 
225— phosphoric  acid,  224— po- 
tassa,  225 — statement  of  analy- 
sis,  illustrated,    225  — tariff  of 

prices  for  valuation  of. 22G 

Manure  of  the  farm-yard,  213— am- 
monia in,  214 — aqueous  extract 
of,  214 — ash,  carbonic  acid,  213 
—insoluble  part,  214, 210— nitro- 
gen, organic  matter,  213— state- 
ment of  analysis,  illustrated, 
217 — sulphur,  sulphuric  acid  in, 

214— Avatcr 213 

Marl,  alkalies  in,  207  —  carbonic 
acid,  20G — humus,  208— lime  and 
magnesia,  207 — nitrogen,  208 — 
phosphoric  acid,  207— silt  analy- 
sis of,  205— water 200 

Marl,  burned 208 

Meal  (see  also  seeds) 2G2 

Measurement  of  solutions 40 

Mercuric   nitrate  as    reagent,  17 — 

standard  solution  of 122 

Mercurous  nitrate  as  reagent 17 


Milk,  albumen  in,  ash,  casein,  263 — 
fat,  264,  265— lacto-protcin,  etc., 
266— pi-otein  compounds,  2G3— 
sugar  (lactose)  2GG— VogeFs  op- 
tical test,  265— water 203 

Milk  of  lime  as  reagent 17 

Nesslcr's  solution  as  reagent,  55 — 

estimation  of  ammonia  witli. ..  58 
Nitric  acid  as  reagent,  8 — estima- 
tion of  by  fusion  of  nitrate  with 
silica,  92— by  insolubility  of  am- 
nionic nitrate  in  alcohol,  93 — 
by  Schlussing's  process,  89— in 
beets  260— in  Chili  saltpetre, 
240— in  farm-j-ard  manure,  215— 
in  fodder  aqueous  extract,  255— 

in  soil 185 

Nitric  acid,  reactions 88 

Nitrogen  in  beets,  258  —  in  bone- 
black,  230— in  bone-meal,  228 — 
in  commercial  manures,  225 — 
in  fodder,  252,  254— in  guano, 
232  — in  manure  of  the  farm- 
yard, 213,215,  216— in  marl,  208— 
in  soil,  173— in  superphosphate, 

235— in  urine 219 

Nitro-hydrochloric   acid,   sec  aqua 

regia 

Nitrous  acid  in  water 273 

Organic  matter,  estimation  by  igni- 
tion in  muffle,  149— ignition  in 
platinum  dish,  149— by  titration 
with  potassic  permanganate, 
151— in  manure  of  the  farm-yard, 
213,  215— in  soil,  183— in  urine, 

218— in  water 272 

Oxalic  acid  as  reagent,  9— estima- 
tion by  conversion  into  carbon- 
ic acid,  101— by  titration  with 
potassic  permanganate,  100 — in 
guano,    233— reactions  of,  99— 

standard  solution  of 50 

Oxygen,  preparation  of 17 

Pea,  as  fodder  plant,  statement  of 

analysis  of 257 

Peat  ashes 250 

Pectose  in  beets 258 

Peruvian  guano 232 

Phosphate,  see  superphosphate 

Phosphatic  guano 234 

Phosphoric  acid,  83— elimination  by 
ammonic  molybdate,  85, 157— by 


302 


INDEX. 


ferric  chloride,  Bodic  acetate, 
magnesia  mixture,  and  citric 
acid,  159— by  metallic  tin,  155— 
in  presence  of  large  excess  of 
ferric  oxide,  100— when  it  alone 
is  to  he  estimated,  159 — estima- 
tion as  magnesic  pyrophosphate 
84  —  by  volumetric  process, 
86— in  hone-black,  230— in  bone- 
meal,  22S — in  commercial  ma- 
nures, 224— in  coprolites,  231 — 
in  guano,  232— in  marl,  207— in 
phosphorite,  231— in  superphos- 
phate, insoluble,    236— soluble, 

235— in  urine .  .222 

Phosphoric  acid,  reactions  of, 83 

Phosphorite,  complete  analysis  of, 

231— phosphoric  acid  in 231 

Phosphorus  salt,  as  reagent 18 

Piknometcr 23 

Plant  ash,  see  ash  of  plants 

Plant,  chlorine  in,  245,  246— sulphur- 
ic acid  (ready  formed),  245— to- 
tal snl phur 245,  246 

Platinum  crucibles,  care  of. 40 

Platinic  chloride,  as  reagent ,  18 

Plumbic  acetate,  as  reagent,  binox- 

ide,  oxide 18 

Potash  compounds,  commercial 239 

Potassic  acetate  as  reagent,  18— bi- 
sulphate,  chromate,  chlorate, 
dichromate,  fcrricyanidc,  ferro- 
cyanide,  hydrate,  iodide,  per- 
manganate, 19— and  sodic  car- 
bonate,   and     sodic     tartrate, 

sulphocyanate 20 

Potassium,  elimination  from  mix- 
ture of  metals  by  milk  of  lime, 
157  —  by  oxalic  acid,  158  — by 
platinic  chloride,  159— from  sili- 
cates, 76 — estimation  as  chlor- 
ide, 45  —  as  potassic  platinic 
chloride,  46— sulphate,  46— by 
titration  with  standard  acid,  47 
—in  ashes  of  fuel,  249— in  Chili 
saltpetre,  239  —  in  commercial 

manures,  235— -in  water 272 

Potassium,  reactions,  44— separa- 
tion from  sodium  by  indirect 
determination  as  chloride,  53 — 
as  sulphate,  53  — by  platinic 
chloride . .   52 


Potassium  and  sodium,  conversion 
of  mixed  sulphates  into  chlor- 
ides    53 

Potatoes,  dry  substance  in,  soluble 
in  water,  protein  compounds  in, 

261— starch,  262— water 261 

Precipitation 29 

Precipitates,  ignition  of,  Avith  Alter, 
38— after  separation  from  filter, 
38— transferring  of  to  filter,  30— 

washing  of,  32— weighing  of 38 

Protein  compounds,  estimation  of, 
118— in  fodder,  252— in  milk,  263  ^ 
— in  potatoes,  261— in  seeds,  262 

— in  wine,  278 — reactions  of 117 

Qualitative  analysis,  course  of 130 

Quantitative  analysis,  schemes  of...J61 

Quartz  powdered,  as  reagent 20 

Residues,  ignition  and  weighing  of,  38 
Eesults  of  analyses,  calculation  of. .  42 
Rocks,  and  products  of  their  weath- 
ering  205 

Saccharose,  estimation,  110— reac- 
tions  115 

Saccharometer 24 

Salt,  complete  analysis  of,  238— esti- 
mation of  in  butter  and  cheese..  268 
Saltpetre,  Chili,  see  Chili  saltpetre. 
Sand  in  ash  of  plants,  243— in  soils, 

182— separation  of  from  silica..  75 
Schlossing's  process  for  estimating 

ammonia,  50— nitric  acid 89 

Seeds,  ash,  etc.,  dry  substance  solu- 
ble in  water,  in  starch,  water..  .262 

Silica  and  sand  in  ashes 243 

Silicates,  fusion  of  with  sodic  and 
potassic  carbonate,  76 — solution 
of,  74 -treatment  of  with  amnio- 
nic fluoride,  77— with  hydroflu- 
oric acid 77 

Silicic  acid,  estimations  and  reac- 
tions,   74— separation   of    from 

coal  and  from  sand 75 

Silt  analysis  of  marl,  205— of  soils, 
Dietrich's  method,  172— Nobel's 

method 169 

Silver  refuse,  to  work  over 13 

Skin,  powder  of.  as  reagent 118 

Soda-lime  as  reagent 20 

Soda,  standard  solution  of 50 

Sodic  acetate  as  reagent,  20— sodic 
and  amnionic  phosphate,  20— hi- 


INDEX. 


;o3 


Bulpliitc,     carbonate,     hyposul- 
phite phosphate,  nitrate 21 

Sodium,  elimination  of  from  sili- 
cates, 76— elimination  with  milk 
of  lime,  157  — with  oxalic  acid, 
15S — estimation  of  as  chloride, 
or  as  sulphate,  52— by  indirect 
processes,  53— in  Chili  saltpetre,  239 

Sodium,    reactions,    51 — separation 
from  potassium  by  indii'cct  meth- 
od, as  chloride  or  as  sulphate,  53 
—by  platinic  chloride 52 

Sodium,  sulphate  of  converted  into 
chloride 53 

Soil,  absolute  weight  of,  19S— ab- 
sorptive power  of  for  salts,  188 — 
adhesive  poAver  of 200 

Soil  analysis,  experiments  to  be 
combined  with,  200  —  general 
considerations  in  regard  to,  105 
—preparation  of  sample  for 16G 

Soil  analysis,  chemical  part^  prepa- 
ration of  soluti(ms  for,  174 — 
with  carbonated  water,  177— 
with  cold  hydrochloric  acid,  174 
— with  hot  hydrochloric  acid, 
179 — with  hydrofluoric  acid,  181 
— with  phosphoric  acid,  182— 
with  sulphuric  acid 180 

Soil  analysis,  mechanical  part,  168— 
silt  process  by  Dietrich's  meth- 
od,  172— by  NObel's  method,   109 

Soil  analysis,  physical  part,  in  rela- 
tion to  heat-absorbing  power, 
19T— to  heat-conducting  power, 
197 — to  heat-retaining  power,  198 
— consistency,  199— power  of  ab- 
sorbing water-vapor,  192  —  of 
retaining  liquid  water,  193 — of 
retaining  water-vapor,  192— rate 
of  evaporation  of  water  from, 
194  —  readiness  with  which 
water  moves  downward  in,  197 
— readiness  with  which  water 
moves  upward,  196 — readiness 
with  which  water  percolates 
through,196 — volume  when  com- 
pletely saturated  with  Avater,  199 
—porosity,  199— specific  gravity, 
apparent  and  real,  198— tenacity,199 

Soil  analysis,  statement  of  results 
illustrated 188 


Soil,  estimation  of  ammonia  in,  188 
—of  carbonic  acid,  173— chlo- 
rine, 186— ferrous  oxide,  187 — 
hydrated  alumina  and  ferric  ox- 
jdc,  186- humus,  183— nitrogen, 
total  in,  173  — nitric  acid,  185  — 
organic  matter,  183 — sand,  by 
phosphoric  acid,  182  —  sulphur, 
186— water 173 

Solution 25 

Solutions,  division  and  measure- 
ment of 40 

Solutions  standard,  preparations  of, 
48,  55,  67,  70,  86,  95,  100, 113,  122, 
151,266 274 

Solutions,  estimation  of  solid  mat- 
ter in  by  simple  evaporation  on 
water-bath,  148 — after  mixture 
with  gypsum,  149— by  evapora- 
tion in  vaccuo  on  hot  sand,  148 
— to  save  ammonia  that  may  be 
given  off 148 

Specific  gravity  of  liquids,  with  the 
areometer,23— with  the  piknomc- 
ter  or  specific-gravity  bottle,  23 — 
-  of  soil  apparent  and  real,  198— 
of  solids  by  specific  gravity  of 
liquid  of  the  same  density,  25 — 
if  soluble  in  water,  25— by  vol- 
ume of  water  displaced,  24— by 
iveight  of  water  displaced  in 
piknometer,  24— of  urine,  217— 
of  wine,  278— of  wool 270 

Starch,  109- estimation  by  conver- 
sion into  sugar  by  malt,  109— by 
sulphuric  acid,  110  — Dragen- 
dorfl's  process,lll— in  beets,  260 
—in  fodder,  257— in  potatoes, 
262— in  seeds,  262— reactions  of,109 

Starch  paper 21 

Sugar  (see  also  saccharose,  glucose, 
etc.)  estimation  in  beets,  258 — 
in  fodder,  aqueous  extract,  255 
—milk.  266,  267— in  wine .279 

Sulphur,  estimation  in  organic  com- 
bination, 152— in  manure  of  the 
farm-yard,  214— in  plant,  total, 
245— in  soil,  286— in  urine,  223— 
reactions 98 

Sulphuric  acid  as  reagent,  9 — elimi- 
nation of,  157— estimation,  78 — 
in  gypsum,  237— in  manure  of 


304 


INDEX. 


the  farm-yard,  214 — in  plant,  245 
—in  mine,  223— in  vinegar,  208 
— in  wine,  283 — reactions  of,  78 

— standard  solution  of 43 

Superphosphates,  ammonia  in  235— 
ash,  235 — complete  analysis  of, 
23G — nitrogen  in,  235— phosphor- 
ic acid,  insoluble,  236— soluble, 

235— water 234 

Tables 2&4 

Tanner's  bark 270 

Tannic  acid,  as  reagent,  10 — estima- 
tion, 107— in  bark,  270— in  -wine, 
280— occurrence,  145— reactions. 102 
Tin,  as  reagent,  21 — use  to  elimi- 
nate phosphoric  acid 155 

Turmeric  as  reagent 21 

Uranic  acetate  as  reagent,  21— stand- 

ai'd    solution  of 78 

Urea  as  reagent,  22— estimation,  122 

—in  urine,  221— reactions 122 

Uric  acid,  estimation,  105 — in  guano. 
233— in  urine,  221— reactions,  105 

—separation  from  hippnric lOG 

Urine,  ammonia  in,  219— ash  of,  218, 
219  — carbon  in,  223  — carbonic 
acid,  218— chlorine,  220— dry  sub- 
stance in  solution,  218— hippuric 
acid,  221— hydrogen,  223— nitro- 
gen, 219— phosphoric  acid,  222— 
sulphur  and  sulphuric  acid,  223 
—urea,    220— uric     acid,    221— 

specific  gravity  of 217 

Valuation  of  manures 220 

Vinegar,  acetic  acid  in,  268  — free 

sulphuric  acid  268 

VogcFs  optical  milk  test 265 

Washing  bottle 33 

Water  distilled  as  reagent 22 

Water,  hygroscopic,  estimation  of 
by  simple  desiccation  on  the 
water-bath,  147  —  estimation 
when  ammonia  is  present,  147— 


estimation  by  simple  ignition, 
147— estimation  of  in  bark,  270 
—in  beets,  257— in  bone-black, 
230— bone-meal,  228— butter  and 
cheese,267— Chili  saltpetre, 239— 
foddor,251— green  parts  of  plants, 
241— gypsum,  237— guano,  232— 
marl,  206— milk,  203— potatoes, 
261— roots,  241— salt,  238— seeds, 
262— soil,  173— superphosphate, 
234— wool 270 

Water,  estimation  of  ammonia  in, 
272— of  dry  substance  in  solution 
in,  271  —  of  hardness,  Clark's 
method, 274— hardness  byFleck's 
method,  270 — of  lime  in,  273— of 
nitric  acid,  272— of  nitrous  acid, 
273— organic  matter,  272  — the 
same  by  titration  with  potassic 
permanganate,  151 — potassa  in.. 272 

Water,  expulsion  of  from  solutions, 
sec  evaporation — relation  of  to 
soil  in  liquid  form,  193— as  va- 
por  192 

Wine,  alcohol  in,  279— alkalies  in, 
283 — ash  of,  278 — average  com- 
position of,  283 — dry  substance 
in  solution,  278— free  acids  in, 
280— gum  and  sugar,  279— malic 
acid,  282— protein  compounds, 
278— specific  gravity  of,  278— 
sugar,  279 — sulphuric  acid  free, 
283— tannic  acid,  280  — tartaric 
acid 282 

Wolffs  process  for  converting  starch 
into  sugar Ill 

Wool,  estimation  of  ash  of,  270— of 
effect  of  washing  at  the  factory, 
270— water  in,  270— preparation 
of  sample  for  examination 269 

Zinc  as  reagent,  22  —  occurrence, 
146— reactions 72 


ADDENDA 

FKOM     PERIODICALS    RECEIVED    WHILE     THE    FOREGOING 
MATTER   WAS   IN    PRESS. 

Bunsen's  filtration  process;  paj^e  33.  R.  S.  Dale  {Chem.  News, 
Mig.,  Ed.  20,  108)  states,  that  more  rapid  filtration  can  be  obtained  by 
substituting-  platinum- wire  gauze,  for  the  foil  in  the  funnel,  without  any 
more  danger  of  tearing  tlie  paper;  and  tlie  gauze  funnel  can  be  fitted  in 
the  glass  one  with  sufficient  accuracy,  by  means  of  a  cone  of  wood  turn- 
ed to  the  proper  angle.  Undoubtedly,  this  gauze  funnel  can  be  advan- 
tageously used  in  cases  wheie  the  pressure  on  the  liquid  in  tlie  filter  is 
much  less  than  an  atmosphere,  as  when  the  rarefaction  of  the  air  in  the 
filtering  flaslc  is  efi'ected  by  means  of  the  flow  of  water  from  one  bottle 
to  another. 

Standard  acid  and  alkaline  solutions  ;  page  48.  Dr.  Fleischer 
{Chem.  News ;  Am.  Bepr.,  5,  88)  gives  some  good  reasons  for  preferring 
a  standard  hydrochloric  acid,  instead  of  sulphuric;  it  forms  soluble 
salts  with  all  the  alkaline  earths,  is  readily  obtained  pure,  is  estimable 
with  great  accuracy  by  a  standard  solution  of  argentic  nitrate  as  well  as 
by  an  alkali,  and  its  constancy  is  unimpeachable.  The  standard  of  the 
acid  can  be  determined  by  means  of  a  weighed  amount  of  pure  calcic 
carbonate,  that  has  been  slightly  heated,  or  by  the  standard  argentic  so- 
lution. 

For  a  standard  alkaline  solution,  ammonia  has  many  advantages  over 
soda;  it  is  more  easily  obtained  pure,  and  has  so  slight  a  tendency  to 
absorb  carbonic  acid  from  the  air,  that  no  special  provision  need  be  made 
against  it. 

As  some  neutral  amnionic  salts  have  a  slight  acid  reaction  when  the 
solution  is  liot,  the  liquid  to  be  tested  should  be  cold.  A  solution  con- 
taining half  an  equivalent  of  ammonia  in  the  litre,  is  recommended. 

Both  of  these  standard  solutions  should  be  kept  in  a  cool  place,  free 
from  dust.  If  the  aininonic  solution  is  exposed  to  hot  summer  weather, 
the  bottle  containing  it  should  be  placed  in  cold  water  that  is  renewed 
every  day;  by  exposure  to  a  temperature  above  25°  C,  the  standard  of 
the  solution  will  be  very  slightly  altered. 

Estimation  of  iron  by  the  permanganate  process  ;  page  07.  M. 
Moyaux  {Revue  Universelle  des  Mines,  etc.,  Chem.  News,  Am,.  Repr.,  5,  179) 
states,  that  the  useof  ammonio-ferrous  sulphate  to  determine  the  staud- 
305 


306  ADDENDA. 

ard  of  the  peimanganic  solution  is  unsafe,  for  the  reason  that  the  com- 
position of  the  salt  is  not  constant,  and  that,  consequently,  metallic  iron 
or  oxalic  acid  must  be  used.  Fresenius  also,  gives  the  preference  to  the 
use  of  metallic  iron  as  the  most  accurate,  although  perhaps  less  conven- 
ient, method;  he  gives  the  following  directions  for  executing  the  proc- 
ess. Weigh  out  about  0.2  grm.  of  the  finest  piano-forte  v^ire,  free  from 
rust,  and  add  to  it  in  the  long-necked  flask  (p.  68)  20  c.c.  of  dilute  sul- 
phuric acid,  and  as  much  water,  and  proceed  with  the  solution  in  the 
current  of  carbonic  acid,  and  the  subsequent  titration,  as  directed  in  tlie 
case  of   the  use  of  the  ammonio-ferrous  sulphate.      Instead  of   £, 

7 
in  the  proportion  on  page  69,  substitute  F  x  0.997 ;  this  product  is  taken 
as  the  weight  of  pure  iron  in  the  weight  F  of  iron  used,  since  the  purest 
wire  contains  about  0.3o|o  of  impurities! 

In  the  text  (pp.  69,  154)  the  preference  is  gfven  to  a  sulphuric-acid  so- 
lution of  the  ferrous  salt  for  titration  rather  than  a  solution  in  hydro- 
chloric acid.  In  an  appendix  to  his  Quantitative  Analyse^  Fresenius  states, 
that  the  titration  of  a  hydrochloric-acid  solution  is  unreliable  unless  con- 
ducted as  follows.  Make  the  volume  of  the  solution  up  to  a  quarter  of 
a  litre,  add  50  c.c.  of  this  solution  to  a  considerable  quantity  of  water 
acidified  with  sulphuric  acid,  titrate  this  mixture  with  permanganate, 
add  to  it  50  c.c.  more  of  the  ferrous  solution,  titrate  again,  and  so  on 
with  a  third  and  fourth  portion  of  the  same  solution;  finally  use  the 
last  two  results,  the  mean  of  which  multiplied  by  five  will  give  the 
amount  of  permanganic  solution  that  should  be  required  for  the  whole 
amount  of  the  ferrous  solution. 

The  precipitate  op  ammonio-magnesic  phosphate,  in  the  esti- 
mation OP  MAGNESIUM,   PAGE  64,   AND  OF  PHOSPHORIC   ACID,  PAGE  87. 

As  the  results  of  experiments  by  Kubel  and  by  Kiesel  {Fres.  Zeitschrift 
8,  pp.  125,  164),  it  appears  that  the  solubility  of  this  precipitate  in  the 
liquid  in  which  the  precipitation  takes  place,  in  the  presence  of  con- 
siderable amnionic  chloride  and  a  not  too  great  excess  of  magnesic  sul- 
phate, is  very  nearly  compensated  for  by  the  minute  quantity  of  basic 
magnesic  sulphate,  or  of  magnesia,  that  is  precipitated  at  the  same  time; 
hence  the  correction  for  the  imperfect  insolubility  of  the  precipitated 
phosphate  seems  to  be  unnecessary. 

Organic  matter  in  water,  page  273.  R.  Angus  Smith,  who  is  a 
strong  and  earnest  champion  for  the  permanganate  process,  in  the  ex- 
amination of  water  with  respect  to  the  presence  of  hurtful  organic 
matter,  uses  a  stronger  solution  than  Kubel  (see  page  151).  He  adds  2 
grms.  of  the  salt  to  a  litre  of  water,  and  gives  the  following  directions 
for  the  titration : 

To  not  less  than  a  litre  of  the  water  add  a  drop  of  this  permanganate 
solution  ;  stir  the  liquid  well,  and  wait  until  the  color  disappears,  and 
proceed  in  this  manner  as  long  as  the  color  disappears  quickly,  say  in  a 
minute  or  two  ;  generally,  considerable  permanency  of  color  is  obtained 


ADDENDA.  307 

in  10-15  minutes.  Then  add  3  "rms.  of  sulphuric  acid  to  the  liquid  and 
proceed  to  add  more  permanganate  in  the  same  manner  as  before. 

According  to  Dr.  Smith,  the  oxygen  of  tlie  permanganate  used  hefoi'e 
adding  the  acid,  was  taken  up  by  products  of  putrefaction  in  solution  in 
tlie  water,  such  as  sulphuretted  hydrogen,  and  that  required  after  the 
addition  of  the  acid,  was  consumed  by  easily  oxidizable  organic  (animal) 
matter;  all  matters  that  thus  act  speedily  on  the  permanganate  are  the 
most  harmful  in  a  sanitary  point  of  view. 

.  According  to  this  writer  and  to  W.  A.  Miller  also,  the  results  obtained 
can  be  expressed  more  accurately,  by  giving  instead  of  the  number  of 
cubic  centimetres  of  permanganic  solution  used,  the  amount  of  availa- 
ble oxygen  therein — of  which  each  cubic  centimetre  contains  0.005 
grm. 

Dr.  Smith  estimates  the  nitrous  acid  in  the  water  roughly,  by  di- 
luting a  measured  quantity  of  it  until  iodized  starch  i)aper  (paper 
dipped  in  a  solution  of  potassic  iodide  containing  a  little  starch)  is 
no  longer  colored  blue  by  it,  even  after  a  contact  of  several  minutes; 
this  diluted  solution  then  contains  about  one  part  of  nitrous  acid  in 
100,000  of  water,  and  upon  this  basis  the  proportion  in  the  water 
before  dilution  can  be  estimated.  {Chem.  News  Am.  Repr.  5.141,  Eny. 
Ed.  20.113). 


VALUABLE    AND    BEAUTIFUL   WORK. 


HARRIS' 

Insects   Injurious   to  Yegetation. 

BY  THE  LATE 

THADDEUS  WILLIAM  HARRIS,  M.D. 

A  New  Edition,  enlarged  and  Improved,  with  additions  from  the  anthor'i  ^ 
manuscripts  and  original  notes. 
Illustrated  by  engravings  drawn  from  nature  under  the  supervision  of 

PKOF^ESSOR.     J^GJ-ASSIZ. 

Edited  by  CHARLES  L.  FLINT, 
Secretary  of  the  Massachusetts  State  Board  of  Agriculture. 

O  OnSTTEJ  IsTTS. 
CHAPTER    I. 

INTRODUCTION.— Insects  Defined—Brain  and  Nerves— Air-Pipes  and  Breath- 
ing-Holes—Heart and  Blood— Metamorphoses  or  Transformations— 
Classification :  Orders  and  Groups. 

CHAPTER    II. 

COLEOPTERA.— Beetles— Scarabasians—Gi-ound-Beetles— Tree-Beetles— Cock- 
chafers—Flower,  Stag,  Spring,  Timber,  Capricorn,  Leaf-mining,  and  Tor- 
toise Beetles— Chrysomelians—Cantharides. , 

CHAPTER    III. 

ORTHOPTERA.— Earwigs  —  Cockroaches-  -  Soothsayers  —  Walking-sticks  or 
Spectres— Mole,  Field,  Climbing,  and  Wingless  Crickets— Grasshoppers- 
Katydid— Locusts. 

CHAPTER    IV. 

HEMI PTERA.— Bugs— Squash-Bug—Clinch-Bug— Plant  Bugs— Harvest  Flies— 
Tree-Hoppers— Vine-Hoppers— Plant-Lice— American  Blight— Bark-Lice. 

CHAPTER    V. 

LEPIOOPTERA.— Caterpillars  — Butterflies  — Skippers  — Hawk-Moths— ^ge- 
rians  or  Boring  Caterpillars— Moths— Cut-Worms— Span- Worms— Leaf- 
Rollers— Fruit,  Bee,  Corn,  Clothes,  and  Feather-Winged  Moths. 

CHAPTER    VI. 

HYMENOPTERA— Stingers  and  Piercers— Saw-Flies  and  Slugs-Elm,  Fir, 
and  Vine  Saw-Fly  —  Rose-Bush  and  Pear-Tree  Slugs— Horn-Tailed 
Wood-Wasps— Gall-Flies— Barley  Insect  and  Joint  Worm. 

CHAPTER    VII. 

DIPTERA.-  Gnats   and   Flies— Maggots    and   their    Transformations— Gail 
Gnats— Hessian,  Wheat,  and  Radish  Flies— Two- Winged  Gall-Flies,  an^ 
Fruit-Flies. 
APPENDIX.— The  Army  Worm. 

Published  in  two  beautiful  editions ;  one  plain,  with  steel  engravings,  8vo, 
•xtra  cloth,  $4  ;  the  other  in  extra  cloth,  beveled  boards,  red  edges,  engrav 
Inga  colored  with  great  accuracy,  $6. 
Sent  post-paid  on  receipt  of  i>rice. 

ORANGE  JUDD  &  CO., 

24.5  Broadway    New- York  City 


HOW   CROPS    GROW. 

On  tlie  Cliemical  Compsitioii,  Strnctnre,  ana  Life  of  the  Plant, 

FOR   ALL  STUDENTS  OF   AGRICULTURE. 

WITH  NUMEROUS  ILLUSTRATIONS  AND  TABLES  OF  ANALYSES. 

BY 

SAMUEL,    W,    JOH^VSON,    M.A., 

PROFESSOR  OF  ANALYTICAL  AND  AGRICULTURAL  CHEMISTRY  IN  YALE  COLLEGE  ; 

CUEMIST  TO  THE  CONNECTICUT  STATE  AGRICULTURAL  SOCIETY  ; 

MEMBER  OF  THE  NATIONAL  ACADEMY  OF  SCIENCES. 

Tliis  is  a  volume  of  nearly  400  pages,  in  whicli  Agricultural 
Plants,  or  "  Crops,"  are  considered  from  three  distinct,  yet  closely 
related,  stand-points,  as  indicated  by  the  descriptive  title. 

THE  CHEMICAL  COMPOSITIOX  OF  THE  PLVXT. 

lat— The  Volatile  Part. 

2d. — The  Ash — Its  Ingredients  ;  their  Distribution,  Variation,  and 
Quantities.  The  Composition  of  the  Ash  of  various  Farm 
Crops,  with  full  Tables  ;  and  the  Functions  of  the  Ash. 

3d. — Composition  of  the  Plant  in  various  Stages  of  Growth,  and  the 
Relations  subsisting  among  the  Ingredients. 

THE  STRUCTURE  OF  THE   PLANT  AND   THE   OFFICES 
OF  ITS  ORGANS. 

The  Primary  Elements  of  Organic  Structure. 

TJie  Vegetative  Organs — Root,  Stem,  and  Leaf,  and  their  Func- 
tions ;  and 

The  Beproductive  Organs,  nam,ely,  Flowers  and  Fruit,  and  the 
Vitality  of  Seeds  with  their  Influence  on  the  Plants  they  produce. 

THE  LIFE  OF  THE  PLANT. 

Germination,  and  the  conditions  most  favorable  and  unfavor- 
able to  it. 

The  Food  of  the  Plant  when  independent  of  the  Seed. 

Sap  and  its  Motions,  etc.,  etc. 

The  Appendix,  which  consists  of  twelve  Tables  exhibitincr 
the  Composition  of  a  great  number  of  Plants  viewed  from  many 
different  stand-points,  will  be  found  of  inestimable  value  to  practi 
cal  afifriculturists,  students,  and  theorists. 

SENT   POST-PAID.     PRICE,   $2. 

ORANGE   JUDD    &   CO., 

245   Broadway,  Naw-York. 


FAM  IMPLEMENTS  AND  MACHINERY, 

AND  THE 

Principles  of  their  Construction  and  Use : 

WITH 

SIMPLE  AND  PKAOTIOAL  EXPLANATIOITS 

OF   THE 

LAWS    OF    MOTION    AND    FORC£, 

AS   APPLIED    ON    THE    FARM. 
With  287  Illustrations, 

By    JOHISr   J.    THOMAS. 

— ♦ — • 

CONTENTS. 

PART  I.— MECHANICS. 

Chapter  I.— Txtrodtjction. — Value  of  Farm  Machinery— Importance  of  a 
Knowledjje  of  Mechanical  Principles. 

Chapter  II.— General  Principles  of  Mechanics. 

Chapter  III.— Attraction, 

Chapter  IV.— Simple  Machines,  or  Mechanical  Powers. 

Chapter  V. — Application  of  Mechanical  Principles  in  the  Structure  of  Im- 
plements and  Machines, 

Chapter  VI. —Friction. 

Chapter  VII. — Principles  of  Draught. 

Chapter  VIII. — Application  of  Labor. 

Chapter  IX.— Models  of  Machines. 

Chapter  X.— Construction  and  Use  of  Farm  Implements  and  Machines — 
Implements  of  Tillage,  Pulverizers. 

Chapter  XI.— Sowing  Machines. 

Chapter  XII.— Machines  for  Haying  and  Harvesting. 

Chapter  XIII. —Thrashing,  Grinding,  and  Preparing  Products. 

PART  II.— MACHINERY  IN  CONNECTION  WITH  WATER. 
Chapter  I.— Hydrostatics.  ^ 

Chapter  II. — Hydraulics. 

PART  III.— MACHINERY  IN  CONNECTION  WITH  AIR. 
Chapter  I.— Pressure  of  Air. 
Chapter  II. — Motion  of  Air. 

PART  IV.— HEAT. 
Chapter  I.— Conducting  Power— Expansion,  Great  Force  of— Experiments 
with— Steam   Engine— do.    for  Farms— Steam   Plows— Latent   Heat- 
Green  and  Dry  Wood. 
Chapter  II.— Radiation. 

APPENDIX. 
Apparatus  for  Experiments. 
Discharge  of  Water  through  Pipes. 
Velocity  of  Water  in  Pipes. 
Rule  for  Discharge  of  Water. 
Velocity  of  Water  in  Tile  Drains. 
Glossary. 

JPrice,  Post-paid,  $1.50. 

ORANGE   JUDD   &   CO., 

245  Broadway,  Xew-York. 


DOWNING'S 

FRUITS  AND  FRUIT  TREES 

BY 

A.    J.    DO^^^lSrilSiG-. 
Newly  Hevised  and  Greatly  Enlarged 

BY 

CHAl^LES    DOWlSriNG^. 

Octavo,   1122    pages. 


The  original  work  of  the  late  A.  J.  Downing  appeared  in  1845.  Some 
years  after  it  was  revised  and  much  enlarged  by  his  brother,  Charles  Downing, 
who  has  again  completed  the  work  of  a  second  revision,  Charles  Downing  is 
upon  all  hands  acknowledged  as  one  of  our  highest  pomological  authorities. 
He  writes  but  seldom,  but  whatever  bears  his  name  is  accepted  as  the  judg- 
ment of  one  who  is  entirtly  disinterested,  as  far  as  the  commercial  aspects  of 
pomology  are  concerned.  The  present  edition  contains  the  results  of  many 
years'  labor  and  experience,  which  have  been  devoted  to  testing  the  value  of 
fruits,  and  acquiring  a  knowledge  of  them  that  should  benefit  others. 

Recommendation  from  Hon.  MARSHALL  P,  WILDER,  President  of  the 
American  Pomological  Society. 

Boston,  October  4, 1869. 
Gentlemen  :  I  have  received  a  copy  from  Mr.  Charles  Downing  of  the 
second  revised  edition  of  "  Fruits  and  Fruit  Trees  of  America.'"    It  is 
the  most  comprehensive  of  any  similar  work— in  fact,  a  complete  Ekcyclo- 
pedia  of  American  Pomology  brought  down  to  the  present  time. 

The  original  edition  by  his  brother,  the  late  Andrew  Jackson  Downing, 

popular  as  it  ever  has  been,  is  made  doubly  interesting  and  useful  by  this 

revision,  comprising  as  it  does  the  results  of  a  long  life  of  critical  observation. 

As  a  work  of  reference,  it  has  no  equal  in  this  country,  and  deserves  a 

place  in  the  library  of  every  pomologist  in  America. 

MARSHALL  P.  WILDER. 

This  elegant  and  valuable  work  will  be  an  indispensable  requisite  to  every 
library,  and  to  all  interested  in  Fruits  or  Fruit  Culture. 

Price,  prepaid,  $7.50. 

ORANG-E    JUDD    &   CO., 

245  Broadway,  New-TorJc, 


NEW  AMERICAN  FARM  BOOK. 


ORIGINALLY  BT 


H 


^luLElN, 


AUTHOR  03"    "diseases  O:!'  DOMESTIC  ANIMALS,"    AND  FORMERLT  3DIT0B  OF 

THE   "AMERICAN  AGRICULTURIST.'" 

REVISED  AND  ENLARGED  BT 

AUTHOR  03'   "AMERICAN   CATTLE,"   EDITOR  OI!'  THU    "AMERICAN  SUORT-HORN 
HERD   BOOS,"   ETC. 

C  O  jNTTEJI^T  S: 


Introduction.  —  Tillage  Iliisbanclry 
— Grazing  —  Feeding  —  Breeding  — 
Planting,  etc. 

Chapter  I. — Soils  —  Classirication — 
Description  —  Management  —  Pro- 
perties. 

Chapter  II. — Inorganic  Tilanurcs — 
Mineral  —  Stone  —  Eartli  —  Phos- 
phatic. 

Chapter  III.  —  Organic  Manures  — 
Their  Composition  —  Animal— Ve- 
getable. 

Chapter  IV. — ^Irrigation  and  Drain- 
ing. 

Chapter  V. — Mechanical  Divisions 
of  Soils  — Spading  — PlOAving— Im- 
plements. 

Chapter  VI. — The  Grasses — Clovers 
—  Meadows  —  Pastures  —  Compara- 
tive Values  of  Grasses— Implementa 
fjr  tlieii'  Cultivation. 

Chaptjjp.  VII.— Grain,  and  its  Culti- 
vatiaa  —  Varieties  —  Growth — Har- 
vesting. 

CHAPrEn  VIII.— Leguminous  Plants 
— Tne  Pea— Bean  —  English  Field 
B3an— Tare  or  Vetch— Cultivation 
—Harvesting. 

Chapter  IX. — Roots  and  Esculents- 
Varieties— Growth  —  Cultivation  — 
Securing  the  Crops — Uses— Nutri- 
tive Eq[uivaleuts  ot  Different  Kinds 
of  Forage. 

Chapter  X. — Fruits— Apples— Cider 
— Vinegar— Pears— Quinces— Plums 
Peaches  —  Apricots  —  Nectarines  — 
Smaller  Fraits— Planting— Cultiva- 
tion—Gathering— Preserving. 

Chapver  X[.— Miscellaneous  Objects 
of  Cultivation,  aside  from  the  Or- 
dinary Farm  Crops— Broom-corn- 
Flax— Cotton— Hemp-Sugar  Cane 
Sorghum— Maple  Sugar  -Tobacco- 
Indigo— Madder— Wood— Sumach- 
Teasel  —Mustard  —  Hops  —Castor 
Beau. 

Chapter  XH.- Aids  and  Objects  of 
Agriculture  —  Rotation  of  Crops, 
and  their  Effects— Weeds— Restora- 


tion of  Worn-out  Soils — Fertilizing 
Barren  Lands— Utility  of  Birds — 
Fences  —  Hedges  —  Farm  Roads — 
Shade  Trees— Wood  Lands-^Time 
of  Cutting  Timber — Tools— Agri- 
cultural Education  of  the  Farmer. 

Chapter  XIII. — Farm  Buildings- 
House  —  Barn — Sheds  —  Cisterns  — 
Various  other  Outbuildings— Steam- 
ing Apparatus. 

Chapter  XIV.— Domestic  Animals 
— Breeding — Anatomy— Respiration 
— Consumption  of  Food. 

Chapter  XV.— Neat  or  Homed  Cattle 
Devons  —  Herefords — Ayi'eshires  — 
Galloways  —  Short -horns  —  Alder- 
neys  or  Jerseys — Dutch  or  Ilolsteiu  . 
— Management  from  Birth  to  Milk- 
ing, Labor,  or  Slaughter. 

Chapter  XVI.— The  Dairy- Milk- 
Butter — Cheese — Different  Kinds- 
Manner  of  Working. 

Chapter  XVIL — Sheep  —  Merino — 
Saxon — South  Down  —  The  Long- 
wooled  Breeds— Cotswold— Lincoln 
—  Breeding  —  Management  —  Shep- 
herd Dogs. 

Chapter  XVIIT. —The  Horse— De- 
scription of  Different  Breeds— Their 
Various  Uses — Breeding— Manage- 
ment. 

Chapter  XIX. —The  Ass— Mule  — 
Comparative  Labor  of  Working 
Animals, 

Chapter  XX.  —  Swine  —  Different 
Breeds  —  Breeding— Rearing  —  Fat- 
tening—Curing Pork  and  Hams. 

Chapter  XXI.  —  Poultry— Hens,  or 
Barndoor  Fowls  —  Turkey  —  Pea- 
cock—Guinea Hen — Goose  —  Duck 
— Honey  Bees. 

Chapter  XXII.  —  Diseases  of  Ani- 
mals—What Authority  Shall  We 
Adopt  ?  —  Sheep  —  Swine  —  Treat- 
ment and  Breeding  of  Horses. 

Chapter  XXIII.— Conclusion— Gene- 
ral I^marks  —  The  Farmer  who 
Lives  by  his  Occupation— The  Ama- 
teur Farmer— Sundry  Useful  Tables. 


SENT   POST-PAID,  PRICE  $2.50. 

ORANGE    JUDD    &    CO., 

245    Broadway,    NeAV-York. 


AMERICAN    CATTLE; 

Their    History,    Breeding,   and    Management. 

By  LEWIS    F.  ALLEN, 

Late  President   New-York  State  Agricultural  Society,  Editor  "American 
Short-Horn  Herd  Book,"  Author  "  Kural  Architecture,"  etc.,  etc. 

Notices  by  the  Fress. 

We  consider  this  the  most  valuable  work  that  has  recently  been  issued 
from  the  American  press.  It  embraces  all  branches  of  the  important  subject, 
and  fills  a  vacancy  in  our  agricultural  literature  for  winch  work  the  author,  by 
his  manv  years'  experience  and  observation,  was  eminently  tittcd.  .  .  It 
ou-ht  to  be  in  the  hands  of  every  owner  of  cattle,  and  the  country,  as  well  as 
individuals,  would  soon  be  much  richer  for  its  teachings.— Joz/ma^  of  Agn- 
culture,  {St.  Louis.) 

The  lar"-e  experience  of  the  author  in  improving  the  character  of  Ameri- 
can herds  adds  to  the  weight  of  his  observations,  and  has  enabled  him  tx)  pro- 
duce a  work  which  will  at  once  make  good  its  claims  as  a  standard  authorily 
on  the  subject.  An  excellent  feature  of  this  volume  is  its  orderly,  methodical 
arran-^ement,  condensing  a  great  variety  of  information  into  a  comparatively 
smalfcompass,  and  enabling  the  reader  to  find  the  point  on  which  he  is  seek- 
ing light,  without  wasting  his  time  in  turning  over  the  leaves.— iV.  Y.  Tribune. 
"  This  will  rank  among  the  standard  works  of  the  country,  and  will  be  con- 
sidered indispensable  by  every  breeder  of  live-stock.— iVac^ica^  Farmer, (^Fhtla.) 
We  think  it  is  the  most  complete  work  upon  neat  stock  that  we  have 
seen,  embodying  as  it  does  a  vast  amount  of  research  and  careful  study  and 
observation.—  Wisconsin  Farmer. 

His  history  of  cattle  in  general,  and  of  the  individual  breeds  in  particular 
which  occupies  the  first  one  hundred  and  eighty  pages  of  the  volume,  is  writ- 
ten with  much  of  the  grace  and  charm  of  an  Allison  or  a  Macaulay.  His  de- 
scription of  the  leadinj  breeds  is  illustrated  by  cuts  of  a  bull,  a  cow,  and  a 
fat  ox,  of  each  race.  The  next  one  hundred  pages  are  devoted  to  the  sub- 
ject of  Breeding.  This  is  followed  by  chapters  on  Beef  Cattle,  Working  Oxen, 
Milch  Cows,  Cattle  Food,  Diseases,  etc.  The  arrangement,  illustrations,  an- 
alytical index,  etc.,  of  the  work  are  in  the  best  style  of  modern  book-mak- 
ing.— New-England  Farmer. 

The  work  is  one  that  has  been  long  needed,  as  it  takes  the  place  of  the 
foreign  books  of  like  nature  to  which  our  fimers  have  been  obliged  to  ref:^r, 
and  furnishes  in  a  compact  and  well-arranged  volume  all  they  desire  upon  this 
important  subject. — Mains  Farmer. 

Whatever  works  the  stock  farmer  may  already  have,  he  can  not  afford  to 
do  without  this. —  Ohio  Farmer. 

It  is  one  of  the  best  treatises  within  our  knowledge,  and  contains  infor- 
mation sound  and  sensible  on  every  page. — TJie  People,  {Concord,  N.  H.) 

The  object  of  the  work,  as  stated  by  the  author  in  his  preface,  "  is  not  only 
to  give  a  historical  acccount  of  the  Bovine  race,  to  suggest  to  our  farmers  and 
cattle-breeders  the  best  methods  of  their  production  and  management,  but  to 
exalt  and  ennoble  its  pursuit  to  the  dignity  to  which  it  is  cntitlerl  in  the  vari- 
ous departments  of  American  agriculture."  From  the  little  examination  we 
have  been  able  to  give  it,  we  can  not  recommend  it  too  \x\g\i\Y.— Canada 
Farmer. 

Considering  that  there  are  some  ton  million  milch  cows  in  the  United 
States,  and  nearly  a  thousand  million  of  dollars  invested  in  cattle,  the  magni, 
tude  of  this  interest  demands  that  the  best  skilled  talent  be  devoted  to  the 
improvement  of  the  various  breeds  and  the  investigation  of  the  best  method 
of  so  caring  for  the  animals  as  to  gain  the  greatest  profit  from  them.  This 
'  volume  will  give  the  farmer  just  the  instruction  which  he  wants. — N.  T.  Inde- 
pendent. 

Price,  post-paid,  $2.50. 

ORANGE    JIJDD    &    CO., 

245  Broadway,  New- York. 


THE  TIM  BUNKER  PAPERS ; 

Or,    YANKEE    FARMING. 


TIMOTHY    BUNKER,    Esq.. 

OF  HOOKERTOWN,  CT. 

With  Illustrations  by  Iloppin* 


CONTENTS. 


34. 


37. 


A  Stroke  of  Economy. 

Ornamental  Trees. 

Timothy  Bunker,  Esq. 

View  of  the  Bird  Law. 

Guano  in  the  Hill. 

On  Moss  Bunkers. 

On  Subsoiling. 

Going  to  the  Fair. 

In  Tall  Clover. 

On  Horse  Racing. 

At  the  Farmers'  Club. 

On  an  Old  Saw. 

Book  Farming  in  Hookertown. 

Pasturing  Cattle  in  Roads. 

The  Weaker  Brethren. 

Curing  a  Horse  Pond. 

Domesticities  at  Tim  Bunker's. 

Takes  a  Journey. 

On  Farm  Roads. 

A  New  Manure. 

Losing  the  Premium. 

A  New  Enterprise. 

Making  Tiles. 

The  Clergy  and  Farming. 

Women  Horse  Racing, 

Beginning  Life. 

An  Apology  for  Tim  Bunker. 

On  County  Fairs. 

At  Home  A^ain. 

On  Raising  Boys. 

On  Raising  Girls, 

A  New  Case  of  the  Black  Art. 

A  Letter  from  Neighbors. 

The  Shadtown  Parsonage. 

Views  of  Dress. 

A  Rustic  Wedding. 

Saving  a  Sixpence. 

On  Giving  Land  a  Start. 

On  Giving  Boys  a  Start. 

A  Tile  in  the  Head. 

Jake  Friuk  Sold. 

The  New- York  Central  Park. 

On  Irrigation. 


Feeding  with  Oil  Meal. 

The  Farmers'  Club. 

On  Bad  Water. 

Cattle  Disease. 

On  Seed. 

On  Breastworks  In  War. 

Lightning  Rods. 

Buying  a  Farm. 

Topdressing  and  Feeding  After 

math. 
Painting  Buildings. 
The  Value  of  Muck. 
On  Family  Horses. 
The  Horn-ail. 
A  Commentary  on  Roots. 
Stealing  Fruit  and  Flowers. 
The  Cost  of  Pride. 
Swamps  Turning  Indian. 
Tim  Bunker  in  his  Garden. 
On  Running  Astern. 
On  Extravagance. 
The  Fanners  Old  Age.  • 
On  Sheep  Traps. 
Old  Style  Housekeeping. 
On  Keeping  a  Wife  Comfortable. 
Starting  a  Sugar  Mill. 
Reasons  against  Tobacco.  . 
Trip  to  Washington. 
The  Sanitary  Commission. 
Raid  among  the  Pickle  Patches. 
Raid  among  the  Pickle  Patches. 
On  Striking  He. 
Visit  to  Titus  Oaks,  Esq. 
The  Pickle  Fever  in  Hookertown. 
On  Curing  Pickles   and  Eating 

them. 
The  Cotton  Fever  and  Emigration, 
The  Cotton  Fever  and  Emigration, 
The  Food  Question. 
On  Jim  Crow. 
The  Eight-Hour  Law. 
Base  Ball  Clubs. 
The  Rise  of  Real  Estate. 


SENT   POST-PAID.    PRICE,   $1.50. 

ORANGE    JUDD    &    CO., 

24ii    Broadway,   Neic-Tork. 


DARWIN'S  NEW  WORK. 


TME2    T"AK^IA.TIOT^ 

OP 

ANIMALS  AND  PLANTS 

UNDER     DOMESTICATION, 

BT 

CHi^RLES     D^R,"V^I]Sr,     MI.^V.,     y.R.S..     ETC. 

AUTHORIZED   EDITION. 

TT^ITH      -A.      I»  Tl.  IB  T* -A.  O  E 

BT 

PROFESSOR    ASA    GRAY. 

This  work  treats  of  the  variations  in  our  domestic  animals  and  cultivated 
plants,  discussing  the  circumstances  that  influence  these  variations,  inherit- 
ance of  peculiarities,  results  of  in-and-in  breeding,  crossing,  etc. 

It  is  one  of  the  most  remarkable  books  of  the  present  day,  presenting  an 
array  of  facts  that  show  the  most  extraordinary  amount  of  observation  and 
-esearch.  All  the  domestic  animals,  from  horses  and  cattle  to  canary-birds  and 
noney-bees,  are  discussed,  as  well  as  our  leading  culinary  and  other  plants, 
making  it  a  work  of  the  greatest  interest. 

Its  importance  to  agriculturists,  breeders,  scientific  men,  and  the  general 
reader  will  be  seen  by  its  scope  as  indicated  in  the  following  partial  enumera- 
tion of  its  contents  :  Pigs,  Cattle,  Sheep,  Goats  ;  Dogs  and  Cats,  Horses 
AND  Asses  ;  Domestic  Rabbits  ;  Domestic  Pigeons  ;  Fowls,  Ducks,  Geese, 
Peacock,  Turkey,  Guinea  Fowl,  Canary-bird,  Gold-fish  ;  Hive-bees  ; 
SiLK-siOTHS.  Cultivated  Plants  ;  Cereal  and  Culinary  Plants  ;  Fruits, 
Ornamental  Trees,  Flowers,  Bud  Variation.  Inheritance,  Reversion 
OR  Atavism,  Crossing.  On  the  Good  Effects  op  Crossing,  and  on  thk 
Evil  Effects  of  Close  Interbreeding.  Selection.  Causes  op  Variabii.- 
ITY,  Laws  op  Variation,  etc.,  eto. 

Published  in  Two  Volumes  of  nearly  1100  pages. 

IPINEXuY    ILLUSTRATED. 
SENT  POST-PAID, PRICE,  $6.00. 

ORANGE  JUDD  &  CO., 

345   Broadway,   New -York  City 


LIST    OIT 


RURAL     BOOKS 


PUBLISHED  AND  FOR  SALE  BY 

ORANGE     JTJDD     &    CO., 
24.5    BROADWAY,    NEW    YOKK. 

Any  Book  on   tliis  list  will   be   forwarded,  post-paid,  to 

any  address  in  the  United  States,  on  receipt  of  the  price. 


NO. 


Allen's  (L.  F.)  Rural  Architecture.. $1 
Allen's  (li.  L.)  American  Farm  Book  1 
Allen's  New  American  Farm  Book. .  2 
Allen's  (It.  L.)  Diseases  of  Domestic 

Animals 1 

American  Asr.  Annual,  pap.,  50,  clo. 
American  Hort.  Annual, pap. ,50,  clo. 

American  Bird  Fancier 

American  Pomology 3 

American  Rose  Culturist 

American  Weeds  and  Useful  Plants.  1 
Architecture,  (Cummings  &  MiUcr).10 

Architecture,  Modern  Am.,  do 10 

Bement's  Kabhit  Fancier 

Bommer's  Method  of  Making  Manures 

Book  of  Evergreens 3 

Boussingault's  Rural  Economy 1 

Breck's  New  Book  of  Flowers 1 

Buist's  Flower  Garden  Directory....  1 
Buist's  Family  Kitchen  Gardener...  1 
Chorlton's  Grape  Grower's  Guide... 

Cobbett's  American  Gardener 

Cole's  (S.  W.)  American  Fruit  Book 

Cole's  "Veterinarian 

Copeland's  Country  Life,  8vo,  cloth.  5 

Cotton  Culture,  (Lyman) 1 

Cotton-Planter's  Manual,  (Turner)..  1 
Dadd's  (G.  H.)  Modern  Horse  Doctor  1 

Dadd's  American  Cattle  Doctor 1 

Dana's  Muck  Manual 1 

Darwin's  Variation  of  Animals  and 

Plants  under  Domestication,  2  vols.  0 
Dog  &  Gun,  (Hooper's),  pa.  SGc,  clo. 
Downimr's  Landscape  Gardening — 

Draining  forProlltand  Health 1 

Eastwood  on  Cranberry 

EUiott'sWest'n  Fruit  Grower's  Guide  1 
Farm  Impl'ts  «&  Machinery  (Thomas)  1 

Flax  Culture 

Frencli's  Farm  Drainage 1 

Field's  (Thos.  W.)  Pear  Culture 1 


Fuller's  Grape  Culturist 

Fuller's  Small  Fruit. Culturist....... 

Fuller's  Strawberrv  Culturist 

Gardening  for  the  Soutli,  (White)... 

Grciiory  on  Squash  Culture 

Guenon  on  Milch  Cows ... 

Hatris^  Insects  Injurious  to  Vegeta- 
tion, ext.  clo.,  $4.03  ;  col'd  enj^'s.. .. 
Henderi?on's  Gardening  for  Prollt. . . 


Henderson's  Practical  Floriculture.  1 
Herbert's  Hints  to  Horse-Keepers. . .  1 

Hop  Culture 

How  Crops  Grow(Prof.  S.W.Johnson)2 

Hunter  and  Trapper 1 

Jaques'  Manual  of  the  House 1 

Jolmston's  Agricultural  Chemistry..  1 
Johnston's  Elements  of  Agricultural 

Chemistry 1 

Leuchar's  How  to  Build  Hot-Houses  1 

Market  Assistant  (De  Voe) 2 

Miles  on  tlie  Horse's  Foot 

Mohr  on  the  Grape  Vine 1 

My  Vineyard  at  Lakeview 1 

Norton's  Scientific  Agriculture 

Onion  Culture , 

Our  Farm  of  Four  Acres,  pa.  30c.,  clo. 

Pardee  on  Strawberry  Culture 

Peat  and  its  Uses 1 

Pedder's  Land  Measurer ; . ; . 

Percheron  Horse 1 

Quinby's  Mysteries  of  Bee-Keepiug.  1 
Rural  Annual,  (Harris),  8No8.bound, 

2  vols each..  1 

Randall's  Sheep  Husbandry 1 

Randall's  Fine  Wool  Sheep  Husbandryl 
Ricliardson  on  the  Dog,  pa.  30c.,  clo. 

Rivers'  Miniature  Fruit  Garden 1 

Rural  Church  Architecture 12 

Saunders'  Domestic  Poultry,  paper.. 

"  "        cloth.. 

Schenck's  Gardener's  Text  Book.... 

Skillful  Housewife...  

Ste^yart's  (John)  Stable  Book 1 

Tliompson's  Food  of  Animals 1 

Tim  Bunker  Papere 1 

Tobacco  Culture 

Warder's  Hedges  and  Evergreens...  1 
"Woodward's  Cottages&Farm-houses  1 
Woodwaitl's  Suburban  and  Country 

Houses 1 

Woodward's  Country  Homes 1 

W^Ueeler's  Rural  Homes —  2 

Wheeler's  Homes  for  tlie  People 3 

Youatt  and  Spooner  on  the  Horee...  1 

Youatt  and  Martin  on  Cattle 1 

Youatt  on  the  Hog 1 

Youatt  on  Sheep 1 

SPECIAL. 

Woodward's  National  Architect.... 12 


V'^ 


YB  51390 


/ 


I 


